First of all as a Dutchman I really like this idea, however a number of concerns are already raised. Though it is somewhat 'unlucky' to discover the region without finding the best locations...
Yet one aspect, distance, which really is an issue for any European Colony. The most obvious spot for a first Dutch settlement (at least similar to the Cape) would be in modern Western Australia. Though a trading post in the modern Northern territory is a plausible option too.
Actually England wasn't the Netherlands biggest concern, in fact at certain times the North Sea was our pond

, the biggest threat came from the Western European continental hegemon, France.
In fact MarshalBraginsky, have you ever heard of the Netherlands Antilles, a clear inheritance of that era; true the divorce of the jewel of our former colonial Empire the Dutch East Indies, now Indonesia, was somewhat problematic. However that post WW II era period was coloured by the period just before WW II and what happened during the same war.
I also agree with Pompejus, that the Netherlands probably won't get the Cape Colony back, if it got seized; but Australia doesn't have such a position on the trading routes.
Finally though Bill Cameron I never heard that all Cape settlers were from religious minority groups; then again I from a Dutch Roman Catholic background (back then second rate citizens) and at that time Calvinists could split, if a dispute occurred.