It compares very directly to Monument if you have 3 of them in your deck. I think it is interesting, but I'm not sure the upside of being able to buy more than 3 justifies removing the entire +$2 benefit. I'm not sure it would be overpowered to leave the +$2 that Monument has, but it could be knocked down to +$1, or add some other bonus onto the card that helps to mitigate the "no incentive to end the game question.
I don't think there is a major concern with that issue anyway. Again, it compares very closely to Monument, and if the players split the pile, they are only getting 1.33VP per play. Even if one player gets them all (in 2p) they only gain 2.66VP per turn (without villages) which is weaker than buying a Duchy, so I think Provinces will compete pretty well. I think this is actually a pretty weak card if it is left without any other bonus. It might give some incentive to not end the game, but if you are playing to win, you are really going to need to go after the Provinces too.