This already happens to a greater extent than maybe you realise. Witness FreeBSD's adoption of OpenBSD's pf, and so on. Each of the three 'main' BSDs (Free, Net, Open) have a very different focus in terms of the direction of each project, and these idealistic differences - especially when you throw people like Theo de Raadt into the mix - will mean that it's always going to be fragmented in such a manner.

I kind of like it that way, personally.