Well, it's simply a matter of thinking to look in the different places to see how CB has brought things into alignment, but your point that it should all be in one place is an excellent one.
random air number, at least 4 years away. There is plenty that CB want to get out, release N4 (and HSN4, CPN4 etc) would be a big delay to that.
Bostria in the last Q&A video from rumble(I think) listed a bunch of stuff that seems to be a priority ahead of N4, and he only mentioned that in a vague idea of possibly happening in the far off future. That said if CB announced a deluxe collectors rulebook in a year or two including HSN3, the campaign system and the FAQs built in to one massive tome with designers notes so we can see *why* a rule is the way it is rather than just how to play it, I'd be totally behind that...
N3 has all the potential to turn out to be kind of like a PS3* - a long running service platform with lots of hidden potential but that may simply turn out to be a bit too complicated in the long run. * For those who don't know, PS3's chipset was stupidly complicated but if you were a genius at it (and you can fit all those geniuses into a Prius without anyone complaining about space) you could make it jump through hoops that'd put new generation titles to shame - but quicker in execution (the PS4 has reached the point where it'll overtake potential PS3 performance, though, simply by processing power). Making a PS3 jump through those hoops isn't rocket science, though, because rocket science is easy by comparison so the commercial viability for that kind of games would still be a bit... low.
