The father's will is the game's main story and I doubt that'll change soon (or ever). If the condition is something outrageous some people will want to choose to not pursue it and that would create two paths: who's after the will and who isn't. The way the game is designed I don't see us getting two distinct routes.
For that reason I think the condition will be something designed specifically so that everyone, independently from the way they're playing, will agree to being reasonable to do for 5M (possibly 15M).
Personally I think that leaving Monica's house in order to live in the beach house is a given judging by the father's speech.