Well, sure, and Apple would assuredly like everyone to upgrade to iPad Pros, and Nintendo would like everyone to upgrade to New 3DS XLs, but that's not a realistic scenario for a premium product.
Though my question becomes what you expect them to do if that doesn't happen.
True. It will be interesting to see what percentage upgrade, especially in comparison to upgrades to N3DS. That's a pretty unattainable statistic though.
As to the other question it would vary from team to team(not necessarily publisher wide), some would/will probably stay the course, some will make a pivot that overcompensates and some will probably shut down.
Just have to hope the NX isn't coming too late. Publishers have already been transitioning to PS4 only, if they've been upping their technology base to PS4 standards then NX might be hard to fit in release plans. Of course I think that would be bad planning from the developers of that's the case and kind of unlikely.