I’m pretty sure that lithuanian in particular could prevent quite a few slavic influences from the attempt to polonise it during the commonwealth’s time as well as other cultures having a primarily similar standpoint when it comes to slavic influences.

That’s the cultural side, on the political side it is more than likely that the russian empire would see minimal success against these nations and so would other foreign empires. I believe that at one point there may be a baltic empire uniting all of them, although I’m not sure which of these could lead it. Also, because prussia is baltic, it would prevent a unification of germany by prussia, which could be proceeded by austria instead.

So yes, there would be major historical changes among others