Polictical power is with the General Secretary of the CPC, while military power comes from the Chairman of the Central Military Commission. For the last 25 years through 3 presidents, they have been three-in-one, i.e., a person holds the three positions. It has worked well and China has progressed smoothly.
If Xi wants to remain as the General Secretary after 10 years, he can as there is no term limit and I don't think the Central Committee of the CPC will oppose it. So, the term limit of the President has to go or this nice three-in-one situation will be broken.