You may want to take a look at "The Bloody Man" (see my sig)- while I haven't got that far into this particular aspect, a longer-lived William II is a major part of the TL.
Broadly speaking, I think we'd see continued conflict between Stadtholder and States instead of the unexpected collapse of the Orangists as IOTL. This may be pushed to civil war and this is probably the most likely result, but it's possible that William will blunder into an advantageous compromise more by accident than design. The longer the crisis continues, the worse his monetary situation would get (he was a massively wasteful spender), and if he's not careful he'll bankrupt himself. So any conflict has to be a quick one otherwise he's in serious trouble.
If he's in more or less secure control of the Republic by the mid 1650s, I could see William swallowing his hatred of the Republican regime in England and joining them and the French in a war with Spain, the idea being that England gets the Caribbean and France and Holland partition the Spanish Netherlands. The States would hate this, as they were desperate for peace, but they may not be in any position to argue. Elsewhere, Dutch colonies may see more development; William was keen on that sort of thing. I think the United Provinces looks less economically and culturally dominant in the 1650s-1680s, but they're probably more militarily-focused.