Anyway, to elaborate on my Franco-Dutch alliance idea...it would basically be against the British, Portuguese, and Spanish. The Dutch have (through whatever POD you choose-I like the idea, mentioned earlier on this thread, of a failed Dutch colonization of say, Cuba, which teaches them lessons useful in controlling Brazil), a secure colony in northern Brazil. They also have one of the best navies in the world, which would be very helpful to the French.
In Brazil, the Dutch would expand in the north and the French would attack the Portuguese in the south at some point, and (assuming the Franco-Dutch win) Brazil would be divided up between them. In North America, the French have Quebec+Maritimes and the Dutch have New Netherlands-New England is almost encircled. The French and Dutch could launch a joint attack, which if successful would see New England divided between the two (most of it likely Dutch...hardline Calvinists fit into Dutch society much better than French). The French could attack the OTL American south from Saint-Domingue with Dutch naval support and maybe ground troops. I would imagine a lot of it becomes French (to compensate the Dutch getting New Netherlands...though the Dutch maybe get Virginia)
So anyway, by 1750 or so, the English have been kicked out of the Americas (except the Caribbean), the Franco-Dutch have made huge gains (and are probably looking rather distrustfully at each other...doubt the alliance will last). Or, one could do a less extreme version of this senario where the Franco-Dutch make some gains, but not as much as above (which is intended to show the maximum possible success they could have)