China (especially local governments and local corporations) has a lot of debt. But, they also have a lot of assets. China's assets far outweigh their debts. So, China, as a whole, will not be insolvent. Yes, there will be a lot of turmoil, but the debt problem can be paid off.
China's debts are local. It is almost exclusively Chinese borrowing from Chinese. So, if debts aren't paid off (massive defaults) the damage will also be local.
Also, China doesn't import much from the US - less than 1% of our GDP. So, even if China completely disintegrates, we would barely notice it in our GDP.
So, for those reasons, we shouldn't be worried about direct effects. It is indirect effects that we should be concerned with. If China crashes and their currency devalues, then our exports will be harmed outside of just what China imports. Many people would rather buy up Chinese goods for pennies on the dollar instead of US goods. Also, what happens to our treasuries when China sells them en masse? Interest rates will significantly rise and the fed probably can't control them like they have for a century. China owns a lot of foreign currency, expect prices to be volatile as they are sold. Also commodity prices will plunge as China stops buying raw materials, sells off its gold reserves, stops buying so much oil, etc. Finally, expect wages to drop worldwide as the Chinese accept lower wages just to keep a job.
I don't have a good grasp on how bad those indirect effects will be. It probably depends on how fast and how large the bubble burst is. I wouldn't be surprised by a mild recession for the US (or a mild deepening of the recession for the rest of the world).
Finally, I would expect China to get more aggressive militarily. If you can't please your people economically, please them militarily (see Russia in Ukraine for an example).