The only used games I bought recently were 8-32 bits games I wasn't able to find new. The only PS2-or-later game I've bought used were scams on the internet (sold as new by Amazon sellers, but were obviously used).
That being said, I won't buy a game if it may become unplayable in the future, be it 20 or 30 years from now.
I won't buy XBox One. I'll probably buy a PS4, if Sony set the DRM on a per-game basis, and I will only buy games DRM-free. Besides, I'll probably buy a lot of Wii U games, and PC games when there's no DRM and my rig can support it, which means Linux-able (Probably avoiding steam for the same reason of future-proof even if it seems better than Microsoft).
Depending on Sony and 3rd parties on PS4, I'd say something between about the same and a lot less.