Let's imagine that all the Bitcoin devs were arrested by a tyrannical government or bought by an evil mega-corp and forced to change a fundamental aspect of Bitcoin.
Open source doesn't work like that. The code is OSS and anyone is able to modify it and fork it. Current developers (be it Core, XT or whatever) have no more control of it than anyone else. In the end it's always the network that decides. The control is decentralized and collective.
Only way that some goverment could have it's way is if majority of network accepted it or stubbornly kept running a client that is under govt. control. But at any time they would be free to choose otherwise.