The biggest problem is the massive corruption, political leaders and their cronies are riding the gravy train by stealing from EU subsidies, with common people getting shafted, but to keep enough rubes voting for them and keep them on top of the gravy train, they feed the people nationalistic drivel.
In case of Republika Srpska, Dodik has practically cornered himself, by riding on nationalism he kept himself in power, but had to keep pushing, so that he wouldn't be replaced by someone even more radical, so now his own nationalistic policies are threatening to cut of the gravy stream that he relies upon, but if he backs down he will be removed by his voters, so he will need to thread a needle to keep the EU money going and I don't think he is skilled enough to do it.
Croats have it badly, they had to give up their autonomy with Dayton agreement, so Bosniak politicians regularly run roughshod over them. There were talks of reestablishing Herceg-Bosna in some form, but EU leaned on Zagreb to nip idea in the bud.
Bosniak politicians have it easiest, they rode out the big protests in 2014, they control the biggest portion of EU money and have default support of EU and USA.
Unlikely, Russia is trying to work with Serbia and Serbia really doesn't want a Bosnian headache. While Vučić is trying not to offend the the nationalists too much, he made it clear he doesn't want to get Serbia entangled in the Bosnian mess.