Well EU4 and CK2 get lots of free patches up to this day, however they do sell DLC as it means they can continue to devote staff to working on the product.
I am sure once they work out after release the issues going forward they will let us know.
Also a lot of the NF's have to work together or the game is not going to work the way we want. If certain NF's oppose then if one Major takes a NF it might mean that another loses the ability to chose their own NF and this needs to be balanced, just adding custom NFs cause we want them will end up either delaying the product or just stuffing it up.