The reason I suggest itch.io is because they take ~10% cut, compared to Valve and CD Projekt's 30% cut. The developer gets more money.
But if itch.io, GOG or Steam shut down tomorrow... I would not expect to be able to download from them at all. You should install the games on your computer, storing them at your own cost. And if the game is DRM-free, you can still play the game!
Steam is of course very nice in serving re-installs to customers of no-longer-purchasable games. But you can expect that some day it will end. That's why the fight is to have no DRM... to ensure publishers can't "take away" a game already on your computer, or a book already on your e-reader. It's not to demand storefronts let you download your stuff from their servers indefinitely, which is nice but ruinously expensive for them.
But if itch.io, GOG or Steam shut down tomorrow... I would not expect to be able to download from them at all. You should install the games on your computer, storing them at your own cost. And if the game is DRM-free, you can still play the game!
Steam is of course very nice in serving re-installs to customers of no-longer-purchasable games. But you can expect that some day it will end. That's why the fight is to have no DRM... to ensure publishers can't "take away" a game already on your computer, or a book already on your e-reader. It's not to demand storefronts let you download your stuff from their servers indefinitely, which is nice but ruinously expensive for them.