There's a new Gabriel Knight 4 Campaign that was launched a few days ago. It's already been signed by some of the original creators, and re-posted by many of them too. Seems like it might have some legit reason to exist. Anyway, you can sign it from https://www.change.org/p/activision-publishing-gabriel-knight-4-petition

The numbers are going up pretty fast, fingers crossed!

Signed.