China has already tested its 5th generation engine WS-15 in 2010, and the results were very close to their goal. The test thrust was already larger than that of the F-119 used on the F-22.
If the J-20 does enter service 2015-2017 then that is when I expect the 5th generation engine to enter mass production.
Any news when WS-15 will be fitted on the J-20?