The IMF and World Bank can be a real pain in the a** for small countries. Bukele and his administration have made a bold move in legalizing Bitcoin and it's had positive effects on the country's development. As for the next leader, who knows what will happen. But, at least the foundation has been laid and it's up to the next guy to build on it or not. And you're right, let's call it what it is - Bitcoin. No need for all this "cryptocurrency" nonsense.
The next person will also continue what Bukele has done if the next leader has felt such a good impact on his country through Bitcoin. And the next leader will not forget Bitcoin just like that when he sees better developments in his country after adopting Bitcoin.
So I don't think this will change in the next leader because the people of El Salvador have also agreed to this. After all, the residents there can also be used by trading via Bitcoin to circulate their capital and make a profit and that can be an additional job for the residents there.
The IMF, Word bank and other wester powers have been developing systems over more than 50 years in which they manipulate the fuck out of leaders in such ways to incentivize them to act against the interest of their people and their country, and frequently it has been way easier to just go along and get along with the west and the various financial manipulation tools that they use and also the various bullying tools.. so it is not easy for any leader to NOT give into the pressures and to take the easier road to just accept the various kinds of outside money that tends to disallow them autonomy over the governance of their own country... and surely, historically and even into the present, the western powers/institutions will play hard ball including various kinds of disinformation campaigns, too with various leaders who stand up to them or try to exercise sovereignty and/or financial independence.
It seems the hope is that Bukele can hold on and/or that any successor would be strong enough and/or able enough to continue to carry on the kinds of work of self-sovereignty and financial independence and the various ways that Bukele seems to be working that angle.. and it does not seem that Bukele is going to rug pull the El Salvadorean people or to run away with the BTC.. even though there are frequently going to be concerns about these kinds of matters including how much disclosures are being made regarding El Salvador's bitcoin stash.