I don't know if it's true, but I imagine it's the case that most unlicensed stuff like Color Dreams and AVE are on OTP EPROMs. They'd be easy to repair if one knows how, but if they bit-rot I imagine they will become pretty rare in the future unless everyone starts desoldering and replacing the ROMs. I suspect that some 3rd-party games for the Atari 2600 may be in the same boat.
Makes me wonder too if an EPROM bit could get knocked out by cosmic radiation, in that case it may not be safe
anywhere.
I guess the mask-rom carts will be OK if they don't have batteries, but some part of them would succumb to corrosion eventually, and probably the electrolytic cap and SMT parts would get stressed if it was stored without climate control.
Heheh the proven way to preserve it is to do like they did in Sumer. Take a stone cylinder, and inscribe your bits onto it. To make a copy, roll the cylinder across some clay or playdoh or something. That stuff is still somewhat readable after >6000 years, if anyone bothered to try and read it, heheh.