Not much of one, to be honest.
There are several problems with China ever becoming a real threat to the US.
First of all, they have almost no ability to project power. Now granted, on land and to nations they directly connect to they are a serious threat. But they lack the ability to project that power onto any nation that they do not share a border with. And no matter how big their army is, it does not do much good if they can only invade other nations by land.
Secondly, they are very poor at designing their own equipment. For almost everything, they rely upon taking things other nations have built and copying them. Most of their aircraft and ships are literally modifications of old Soviet designs. And they could not even build their own aircraft carrier, once again they bought old Soviet ones. And laughingly, ships that not even the Soviets called "Aircraft Carriers". Their very design (then and now) is called a "Aircraft Carrying Heavy Missile Cruiser". The number and purpose of the aircraft is not to conduct strike missions, but to give the ship some air defense capability. This is why it carries only 26 fighters, where as the USS Nimitz carries 64 (130 if needed with half of that needing to land on a ground base).
And finally, they are entirely dependent upon foreign trade, both for raw materials, food, and the designs of the very things they make for other nations. And aggressive actions on their part would likely see huge parts of the world start an immediate boycott, and their economy would collapse. In face, if they even did a recreation of Tiananmen Square, the same thing would likely happen. The only reason that was not such a big deal is that exports had yet become a major part of their economy. If it was to happen today, it would kill them.
Then finally, there is logistics. The PLAAN (People's Liberation Army Navy) has very short "legs". They have no UNREP capability, have never conducted fleet exercises for more than a couple of weeks, and are even having problems keeping the small number of ships they have active off of the Horn of Africa operating. Their "Navy" has never really been used as a Navy, even in training. It operates more like a heavily gunned Coast Guard than an actual navy. It does have some impressive ships, but without any experience in operating at sea for an extended period of time it is really not that much of a threat in an offensive way.
I have long considered China to be a "Paper Tiger". And their military R&D programs are littered with designs that they promised would be the "best in the world", only to see them scrapped a few years later as they move on to something else altogether. Or shout that some other piece of equipment is the "best in the world", even though it has never actually been fully tested.