They could do an annoying flash forward type of scene or scenes. Personally I am expecting one of those epilogues from 80's high school movies where they show a still picture of a character along with a short "what they did afterwards" explanation.in my opinion the will has too long a completion time to be in the final game....
if MC gives it up right away (most likely if he goes after one of the three girls in the forbidden family, most likely Debbie and Lily) then we'll have no interest as players in who that money goes to
if Mc instead goes for the inheritance (which is possible with many of the secondary girls) it's not like we'll see him collect the first installment after ten years of observing the rules...
so in my opinion something will intervene to make the will "null and void", or at least not important (for example, find out Donald was bankrupt and his money well and truly gone).
It would be cool if the next game they made was a "10 years later" sequel but the variables for that would be insane. Probably best if they just make a new unrelated game.