As we all know, Interplay sadly loses all rights to the Fallout IP Dec 31st 2013.
What exactly is going to happen here? Will GOG try to contact Bethesda to keep the games on?

Also, what will happen to use purchasers? Will we lose access to re download the game?

There is another thread about this. The general consensus is that we really won't know until the first what happened. As for the download being active, other games have been removed before (like XIII) and those who purchased it were still able to download it. This should work the same way.

Obviously GOG does everything in it's power to retain their distributor license but unfortunately the new owner of rights, bethesda, is Steam's lapdog so it's probably extremely difficult, if not near impossible, of a task. As for those users who already have the games in their accounts, they should remain in our accounts (sales are final for both sides and if bethesda forces GOG to remove the game from our account we should make class acction lawsuit againt bethesda for stealing our property). Another bad thing about this is is that GOG will no longer update the game in future (afaik, none of the games removed from catalog had had any updates since removal so far, not even the updated 2.0 installers).