POD should be the Treaty of Breda 1667 which ended the 2nd Anglo-Dutch War. The Dutch had come out on top by destroying most of the English fleet on the River Medway. The English commissioners actually offered to return New Netherland (occupied by England in 1664) if they could have Surinam (taken by the Dutch). Of course a tropical plantation colony was always going to be much more valuable than a settler colony where the main trade appeared to be with the natives for beaver pelts, and the Dutch refused. But supposing they had had an attack of stupidity, and accepted? [Can't you just see Denzil Holles and the other English commissioners congratulating themselves for having put one over on the Dutch? England had lost the war but won the peace!] Perhaps the Dutch East Indian Company adopt this as a way to hurt their rivals in the West India Company?
I then assume that the Dutch would hold New Netherland during the third Anglo-Dutch War in the 1670s. In OTL they actually reconquered and held it until the Treaty of Westminster in 1674 restored the status quo.(This treaty is another possible POD.) In 1680s England and the United Provinces are allied, and from 1688 the Dutch prince William is King of England, so New Netherland should not be at risk. The Dutch should retain it at least until 1720; probably safe until 1780 when there's another war with Great Britain. That's 150-160 years after the colony was first founded.
I recognise that the United Provinces don't have the capacity to pump large numbers of immigrants into New Netherland. They don't have the population and there isn't really the driver of rural poverty, so most increase will be through internal growth. But I assume there will be a continuing trickle of people from the Netherlands going there after 1667. However because of the Dutch reputation for religious tolerance, I do think the colony will prove attractive for Huguenots after 1685. Perhaps the majority of those who went to the Cape in OTL will emigrate to New Netherland, leading to many family names like du Toit, du Plessis, Joubert and Retief. For similar reasons dissident German religious groups like the Amish, Mennonites, Hutterites etc will also find it an attractive venue. And some English dissenters will also go there, as indeed happened before 1664.
So what will New Netherland be like in 1720 or 1780? And the big question: what is the effect on British North America when the New England colonies remain physically separated from the southern plantation colonies by an alien wedge of territory - roughly most of New York and New Jersey? Do they evolve much more separately, with much less common feeling than in OTL? Where does William Penn establish his colony? Is the ARW butterflied away? And would the Haudenosaunee Conferederation have a slim chance of surviving longer, as a sort of buffer state? All very interesting!
