There can be a Victory card that gives points for Curses in your deck. Though that's kind of dumb.
Having a Victory card count the number of coin tokens you have at the end of the game and have that is kinda broken, even if you had it so that it counted every 6 tokens rounded down or something. And also, it's a dead card in your hand if there ARE no Coin Tokens. So then it must hand out coin tokens to use in the first place. Hand out 6, and everyone will buy it for the tokens. Hand out less, and the card sucks, which leads to the natural conclusion that you must make the VP Token count threshold lower. Which breaks the game in the other direction. It's an interesting idea I think, but really, it won't work.
VP that does stuff is likely going to be the main way to go from here on out.
There can be a VP card that grants an extra +1 VP per Reserve Card you haven't used. That's not terribly bad, and it forces you to not want to use Reserves, making it somewhat balanced in use I think. Perhaps this card is a Reserve in itself. If so, it would have to be more expensive (maybe $5 or $6) so that you can't just get VP while having it not clog your deck, and have going for pure Reserve VP the way to go every time it appears. It seems a bit delicate, but I think this is kind of a neat idea too.
VP that is worth +2 that when you trash it, you gain an Estate (or 2) plus some other card? It's interesting for 3-piles for sure.
VP that gives Virtual coin could be explored more, I think. Perhaps a card that is Victory/Action that gives you a few Coin Tokens every time you play it, making you somewhat happy if you draw it in your hand? It would need to be Terminal though for sure, so it sometimes sucks.
VP that has a scout effect?
There are tons of ideas for VP, and goodness knows I've just started.