I think the most optimistic outcome for Bitcoin would be to return to its roots, which is to play to the nature of bitcoin as a currency, as the opposite of global fiat currencies, coexisting with global fiat currencies and ready to replace the declining credit of fiat currencies, such as overissued US dollars.
That would require the majority of Bitcoin holders to refrain from speculative activity. If that happens Bitcoin could become a currency. Otherwise how do you see Bitcoin achieve sufficient stability in order to work as a currency as we know it?
Having bitcoin as a currency would mean reaching its goal already but since the government are greatly opposed with its currency legalization so it's hard for bitcoin to be a global currency.
So people in the crypto community would find other ways to make bitcoin a profitable one by trading or just simply holding. And we can't stop them from doing it because honestly, the best result for bitcoin right now is knowing how profitable it is as an asset or an investment.
I don't know if Bitcoin even needs specific legalization. It already does what it is supposed to do. Provide an alternative investment vehicle that is the only one which is out of government's control.