Li Keqiang said he will step down after his 2nd term ends. So we have the Premier seat, which will be taken by someone. I guess Han Zheng is high possibility, however he is the same age as Li.
It is difficult to say if it is He Lifeng, Liu He or others.
Han Zheng is one year older than Li Keqiang, and one year younger than Xi Jinping. Liu He is actually the oldest of the bunch. One year older than Xi Jinping. I think Liu He will retire. He Lifeng is too inexperienced to take over as premier.
Han Zheng could potentially fill the role, as he's serving his first term in the Politburo Standing Committee. But having him stay while Li Keqiang retiring seems unlikely, as Li is younger.
So two possible scenarios:
1. Han Zheng takes over as premier, Li becomes Chairman of NPC (there's some idiot writing on the Diplomat saying moving from premiership to NPC Chairman is impossible because it's a demotion, but Li Peng did exact that and it wasn't a demotion).
2. Both Han and Li retire. Hu Chunhua takes over as premier.
The first scenario makes Xi's staying less standout (people think Xi and Li are in the same generation), while the second scenario gives people some young faces while maintain some measure of diversity in top leadership (Hu Chunhua is not Xi's man).
There's the possibility that Wang Yang could take over as premier, however even though Wang was the first vice premier before moving to CPPCC, he has been out of the State Council for too long and the premier's role is to keep the central government machinery running. So I consider the possibility of Wang Yang going back to lead the State Council to be extremely low.