When do you think we will get the old MechWarrior games on GOG ?

Ask the IP holders, not GOG.

It's not GOG's decision to make.

And feel free to add them to the GOG Dreamlist.

Unfortunately people have wanted these for many years, and the rights situation is too complex or (more likely) the parties involved aren't interested (especially Microsoft if they indeed hold the rights).

Nevertheless, vote on the Dreamlist if you haven't already:

https://www.gog.com/dreamlist/?title=mechwarrior&show_only_unreleased=1&sort=global_wishlist_votes_count&order=desc (click on "Start Voting")

MehWarrior.