I suspect modern, new manufactured Win 70s will be somewhat collectible as they are hard to find right now. I also suspect several brands of ARs, especially high quality ones will be desirable, since they're the guns that all the 'old' people (in 30+ years) were brought up with, much like baby boomers love the Pre-64s of their youth. If AR manufacturing is ever so severely regulated that they may as well be banned, hopefully today's ARs would be grandfathered in, and I suspect they'd bring a premium. I wonder if any specific cartridge, regardless of which rifle would be desirable?
Anything Tikka, Begera, (new) Savage and maybe even Christiansen (since they're so readily available) I suspect won't be collectible at all.
I wish I had bought all the old Ruger 77 Zytel stocked rifles that I could find...
Back in the 90's, those boat paddle rugers were very easy to find. Generally costing around $369.99. The Browning POS model 70 will never be "collectible".