I wouldn't say the players you mentioned have great reading skills. Yes, they are fine players and most of them late-bloomers and still playing good badminton, but not necessarily because of their reading and anticipation skills.
Yes indeed, I'm being a bit skeptical wether you can improve something like that. Stamina, physical fitness, power or explosiveness, sure, but reading and anticipation sounds very very difficult. I think it's something you either have or don't. Usually the reading comes from playing lots of different players over the years, which Chen Long already did. It's not like he is inexperienced. And we also have to differentiate between reading the game overall and being familiar with one particular players' game (e. g. Chen Long knowing LCW's game through excessive coaching).
Take for example the exercise where you cover the net with a blanket, towel or whatever and the coach plays underhand shots. What they are doing is not improving the anticipation skills, but the players' capability to still react in a reasonable amount of time when being late to the shot. Then there's that other exercise where they do video analysis and show the opponent just before he plays a shot and the player has to decide which shot he is going to play. Now, is that really improving the reading skills in a match situation?
Yes, indeed, reading the opponent's game and anticipation is the most difficult thing to do, I couldn't agree with you more. Still that's what I hope he can improve on the most based on his accumulated experience, maturity and lots of training with players of different playing styles.
Note that Chen Long wasn't particularly good at that aspect of the game in the past and yet he could beat LCW for the three most coveted major titles. But also bear in mind, he didn't just overcome LCW, en route to the final he had to face other tough contenders, so you can't say he's trained specifically to take on LCW alone while ignoring the rest of the opposition as if they posed little to no threat to him. Besides, he wouldn't know in advance (apart from the players list) exactly who he would meet from the opening round to the final. Even after the draw was made, he couldn't be too sure about each possible opponent's form and standard at that time ,e.g., some players might improve their game significantly, less familiar opponents could surprise you (remember how he was stunned by a certain Guatemalan Keven Cordon in 2011 WC, perhaps irrelevant if we only consider his best years), certain opponents might rise to the occasion or play above themselves, not to mention unforeseen circumstances might arise, or whatever.
My point is during those years when Chen Long was in the ascendancy, he and his coaches, Sun Jun and Xia Xuanze, must have done something very right to elevate him to the top of the heap. Personally, I'm hoping he and his coaches can do that again under a new set of circumstances and different challenges. Talking about the need for improving his reading of the game and anticipation ability is just my own wish for him but, I believe, Chen Long himself and his coaches know better, in view of his current situation , his strengths and weaknesses, his shortcoming and limitation, what he can or cannot do ,what areas he can still improve on, such as wider shot variation, a bit more deception, perhaps, play more aggressively, more sudden injection of pace and suchlike, or, generally speaking, adopt a different but suitable gameplan against different opponents according to their playing styles, etc, etc. Just saying.
By the way, for the Rio Olympics, Chen Long specially credited Wang Shixian for his success as he had promised to bring home the gold medal as a gift to her, and,on her part, she actually flew to Rio and stayed in a nearby hotel to cook for him and spend some quality and romantic time with him - the impact of such a motivation cannot be underestimated considering he was among the top three contenders for Olympic gold. In fact as early as the London Olympics 2012, Li Yongbo was openly saying to watch out for Chen Long who might be the one to mount the winners podium for gold but, as we know, he lost to LCW in the semifinals and went on to take bronze beating Lee Hyun Il in the play-off.
To be honest, what irks me the most about Chen Long is that his basic game is very strong but he has a tendency ,I call it a 'bad habit', to play mostly simple, straightforward and all too predictable textbook shots and at a pace that the opponents find comfortable so much so that he often finds himself losing the initiative ,being dictated to, getting entangled and unable to extricate himself. To put it another way, as Li Yongbo impressed upon him at the Rio Olympics after he dropped G2 to Son Wan Ho, the only hiccup to an otherwise perfect rendering from the get-go in the opening round all the way to the final , a consummate display of masterclass badminton at the highest level:" Don't play to the opponent's rhythm, play at your own rhythm." , said during the break before the start of G3. Timely advice that woke Chen Long up, he immediately reasserted himself and stamped his authority on Son Wan Ho to romp home to victory in commanding fashion again.
I know, all that is history now. Admittedly, it seems to me that Chen Long, in spite of his multiple World and Olympic Champion status, is the most under-appreciated and underrated titleholders in recent times, the forgettable Ji Xinpeng, the Sydney 2000 OG gold medallist aside.
Nevertheless, the question is, can he do it again ? Perhaps it's wishful thinking on my part, certainly not fanboyism, it's just not me, but, I'd to think he still has at least an outside, if not realistic, chance of achieving it again. Not a high probability,I concede, but not mission impossible, either.
In reply to your question in the last paragraph, I have only this to say, don't confuse random guesswork with anticipation based on reading the opponent's game, two entirely different matters.
Finally, even if you have a good reading of the game and hence anticipation ability, you are still beatable if other important aspects of your game is not fully up to it. That's why, even Kento Momota, who is highly capable in that regard, was defeated by eight different opponents in the last one year or so when he was on the comeback trail, but discounting 2017 as he was initially struggling to regain his form after a one-year imposed layoff. As Momota himself has given the reasons for each of those nine losses (twice in a row to Anthony Ginting), I shan't presumed to delve into it. Suffice to say that as long as you've a vulnerability, your opponent, while probing for weaknesses discovered it, would definitely waste no time in exploiting it to his maximum advantage.
When even Momota, the most hotshot player the past one year, understands the necessity to continue working on his game, I'm sure Chen Long, despite his manifest accomplishments, is no exception and, for that matter, anyone else. Precisely, the legendary grandmaster Tang Xianhu's sage advice , no less.
Ah, before I forget, it was none other than Super Dan who has said more than once that when he saw Lee CW constantly snapping at his heels, he felt the urgency to be continuously on his toes, and that's what motivated him to be better and better, thanks largely to LCW's great rivalry. You might like to know that in Lin Dan's early years it was first Peter Gade, then Taufik Hidayat, who lifted up his game before LCW took over to become his greatest archrival for many years that comprised the highlights of his glorious career. Pardon my long-winded post.
I've mixed feelings for him, a bit more positive than negative, admittedly. I mean, all these pent-up thoughts and emotions accumulated over the last couple of years released at one go. My apologies for getting carried away.