Agreed, we much more aware of the posible loss of digital heratige through advancements that more care is being taken to preserve it.

In 20 years time a neural net or quantum computer will be able to emulate the hardware/software of today.

Okay, but in the end your Commodore 64 (ooh, nostalgia !) will cease to work and with it, into oblivion, your games will go. Mind you, you've got 2 so you might be okay.

Your games will last for as long as your hardware will last. That's the bottom line when it comes to computer games. Books are (or were - we now have the Kindle) written on paper. Paper doesn't last forever but it takes a long time to biodegrade and it never gets upgraded, nor does the stuff which is printed on it ever need to be made compatible with new paper. Paper is paper is paper. Computer games depend for their existence on their compatibility with hardware which is constantly changing and rendering older games obsolete, or difficult to play. So, regardless of any retailers' policies, the life of a game (and of a gamer's catalogue of playable games) is inevitably limited. It sucks, but it's true. It came with the territory right from the beginning.

I wonder if my G.I. Joe fan club membership has expired?

In England it was called "Action Man". Another wonderful / utterly dreadful American import !

You have heard about emulation, haven't you?
Not depending on original hardware is what all the emulators like DosBox, Snes9x, Vice, fceux, pcsx-reloaded, pcsx2, etc... are for. Compatibility layers like WINE make really old Windows games run under Linux while they don't even run on modern Windows anymore, etc... Even the handheld scene has compatibility layers like GINGE and emulators. Even a 3DS-XL can play NES, GameBoy, GameBoy Color amd GameBoy Advance just fine. Big companies don't care for backwards emulation since they aim to be able to sell the same games to the same people over and over again, but there are always enough people trying to preserve things by excellent work they are mostly even doing for free.

Of course OpenSourcing software after a reasonable amount of time would be a way to go too (any program could be ported to modern hardware this way) but since not many companies are willing to do that, emulation it is.

Without DosBox, GoG would need to get the devs and rights holders of the old games here write new ports or open source their code and let GoG take care of porting, so even GoG is strongly depending on emulation right now and while the commercial use of it is a new trend, emulation itself isn't, because not many people really want to have 5 generations of computers at home or give up their old games.

Yes, I've heard about emulation, but I know next to nothing about it. I don't have a background in computers, so every time I have a problem getting an older game to work I have to make a big effort to make it playable. I managed to install MAME once to play the old arcade game Mr.Do, but I've totally forgotten how I did it. Well, that sounds hopeful then, but how future proof is it ?

we need to petition cd projekt red to pledge to open source all of their games 50 years after release. though at the rate of technology change, 25 years may be too long (commodore64 was top of the line 33 years ago)

I understand that in about x years these games would not be playable for example 65 years or so .... my question go more to exceptions like someone who has a big collection of games at gog and dies from accident or from illness .... knwoning that on statistics the chance you have a accident is 1 on 128 on life time....... it would be a shame that with this person the whole collection would go in the nothing ....

IIRC Action Man was an English Version made by a different company.

To give you a serious answer to your question, GOG really has no policy for that whatsoever as far as I know. They've only been around for a few years, so it's not like they've actually had to deal with such a thing, but then, a lot of websites don't. Honestly, your best bet is to write your username and password down somewhere and either leave it for somebody to find after you die, or stipulate in your will that you want a certain person to have the games on said account.

I see no reason to not make them OpenSource immedeately or after 5 years max, they don't have to make it freeware.
People often forget, that OpenSource isn't automatically freeware.
I doubt that anyone would actually go through a source code of a big game and try to build and sell something else on top of it without being allowed to use any assets or parts of this code.
It's really just for longevity and compatibility.

The source code for Aquaria has been released relatively soon after release and thanks to this, the community was able to fix some things. Nobody made money because of the open sourcing afaik and the dev rather gave the source than continued support for the game, so it's really a win/win situation for everyone as long as a decent support period by the devs is granted before they pass it on to the community.

The code can be open source, while the asset files remain copyrighted

That's what I've said.

That's the usual case of open sourced commercial games, here's a list of games where this happened:
https://en.wikipedia.org/wiki/List_of_commercial_video_games_with_available_source_code