I was kind of hoping that he was just like his dad. Poor and from an "ordinary" background. If the letter tells him he is inheriting massive amounts of money that would just make him a VN cliché of a rich young guy with a massive pole. Booooooooring. So I hope the letter says something different or if there is some money coming his way it would be just enough for him to make a decision between helping his dad or pay for his tuition or help Maya. I would rather he finishes Uni and works his way to help his dad rather than just being another "lucky" boy.
it is a certainty that his mother's family was rich, and surely the letter has something to do with that.
I also hope it does not change the social status of MC, in my opinion it would distort his character who for now is a hero for what he does and says, not for what he gives and spends
it will probably lead to some tension with his father anyway (either because of something he hasn't told him or the attraction the new family may have on him).
I believe that basically the letter will create a dilemma for MC, between accepting the advantages of the new family but at the cost of changing their life (changing college? changing fraternity? getting away from father?)
I still don't see what it would be like if MC found out he was a Burgmeister and not a Bezos or whatever. but it can be, and it would make the BADIK world more cohesive but smaller.