Not sure if China could avoid their loss in the 2003 Sudirman Cup by fielding different players. At that Kim/Ra was unbeatable, and team China is weak in MD at that time. The scratch pair of Cai Yun/Zhang Wei played well, but Lee/Yoo was still a bit too strong for them.
The only way China can win the Sudirman Cup in 2003 is for them to win MS, WD, and WS. Lee Hyun Il did pull the upset by beating Chen Hong, but who else could China field at that time MS? Lin Dan and Bao Chunlai were no at their peak yet. Xia Xuanze might be an alternative, but I don't see why it would be better to field Xia instead of Chen at that time.