sure they can leave..but 1 ..takes time and A LOT of money...if they do, most likely the chinese gov wont allow imports of products from those companies. , even go as far as bar exports or selling of chinese produce products to those companies that they need to make their own products. (rare minerals, special quemicals etc etc).Why not? Western companies, yes including TWDC, can pack up and go anywhere they want globally to produce their products. Plenty of countries that will welcome them to everyone's mutual benefit.
and any big companie that has no access to the chinese market this day its doomed to fail. period.
so they would be shooting themselves in both feet and knees at the same time. so, nope it just wont happen.