They have 35 back to back wins since Oct 2013. Will it end in All England 2014? http://www.bwfbadminton.org/ranking.aspx?id=70&dt=5&pid=143807
They are clearly the 2nd best team in the world right now, despite their world rank. But I think they will still lose to YY/WXL at the All England. Tang isn't at Wang Xiaoli's level yet, especially in smash power.
Also of interesting note: Tang Jinhua is currently world ranking #3 with Ma Jin and #5 with Bao Yixin at the same time! Pretty remarkable year for her.
and for the XD, Bao is at #26, #113 and #360. therefore she featured in the world ranking lists with 7 different partners!
I think the winning streak will end at the AE. If nothing else, I think CBA would like YY/WXL to retain the title. Nonetheless, it's a pretty remarkable win streak across tournaments for Bao/Tang.
Tang / Bao got defeated in the World Champ.. Looks like they are not performing too well this year. http://www.badzine.net/news/worlds-r32-top-seeds-tang-bao-bow-out/31982/