It is possible, but many countries already legalize crypto. If in a country the government prohibits the developers, then they can move to another country that is crypto legal there. For example like Binance ever did, they move from China to another country that accepts crypto projects/companies. So, there is still a chance for the developers to create new crypto coins. We don't need to worry so much.
It is possible, but in the other sense this is to maintain those new projects that don't have any other thing to do but to scam people. But if it's a legit company that they've stopped.
That's what they're going to do and fly around to nearby country where they're allowed to make it. But I think that's too much for them if they're just a new coin and starting out.
Legal harmonization will be a big problem not for us, but for regulators. They can't really prohibit anyone from writing the code, but only from publishing it, but what would happen then if exactly as you say go to a country where it is allowed and publish it there? Even if you return, on what legal grounds are they going to sue you? It's is going to be almost impossible for them to forbid writing code.