Of course nothing is taken for granted, both US and China have a lot of challenges ahead of them, but in my opinion China has a potential of to overtake US in prospect of few decades.Ehhh it depends. While I see a rivalry happening, I don't see China exceeding the US in being a superpower. China still has its disadvantages (like only 10% of its land being good enough to grow food if I remember correcly) and there's also the nations having to transition into the service economy and who could do it first. The legacy of the British Empire means alot of the stuff will still be Anglophonic to some level.
China may have a bit more of a difficult time adjusting to the new focus of service as the economy and I think the US will still have the advantge over in digital stuff. This China has not made the litany of mitakes like OTL China has. That said, they will still have their problems, issues and so on to deal with, especially with rising social movements and the like.
Naturally, I am using OTL China as comparison. Both states share some problems, some are unique for OTL or TTL, but my point is TTL China has bigger economic, industrial and most importantly demographic advantage over OTL China. So we will see how the situation will develop.