I have a lot of Steam games. I'm not happy with them, but sorta trapped over there.
If there were an option to convert my entire Steam library to GOG, I'd jump on it.
I'd even pay up to a few hundred dollars for that service.

For every game that you can confidently conclude will never be here, there are other ways to Unlock your Steam games.

What do you mean by confidently conclude?

Able to deduce beyond reasonable doubt; to possess evidence in favour of a game not being published on GOG in the future, a statement confirming this from the developer/publisher, perhaps.

Usually, i would say the "FromSoftware" games will never be here. However, the same i already had in mind for many other games and all of a sudden they started appearing here. For example many of the Sony-titles: God of War, Days Gone, Uncharted... and some more.

It actually even was a surprise Horizon Zero Dawn was coming to this platform, something i would never have guessed back at the old days still without a PS5 released. There are way more actually "AAA" titles released here i never had in mind it would happen.

On the other hand, many "Indie"-titles for example the new Supergiant games (not a true Indie anymore, yet a small studio still) and as well "Sabotage Studio" games which has been released in the past but all of a sudden they stopped supporting GoG. Even many more Indies "Signalis" for example... they even was supporting MS instead, which is, at least on PC (not even on consoles... lets be honest), not popular at all. They apparently turned to become "DRM friendly" all of a sudden and perhaps GOG was to less coins... as they simply had "more rewarding" options... Switch for example, which is currently the big "Indie cash cow".

So, the future can always be a surprise. Perhaps we may even see Black Myth Wukong at some day far into the future here, but most likely never again another Hades or Signalis. So i would always be careful with "predictions" and simply enjoy the good games i may get.

I think we can confidently conclude that Portal will never be on GOG

A Valve title? Ok, you won!

Would literally make me lol if we got Half Life....

This would need DRASTICAL changes. As long as the majority of gamers is satifsfied with consuming games instead of owning something, i guess no one can break the Steam dominance.

The weak spot is truly... the "ownership".