Asked about a release date on SteamCommunity.com for the Serious Fusion 2017 update to Serious Sam HD, Croteam's Alen Ladavac wrote this less than an hour ago, "The date hasn't been announced yet, but the build is ready. We are just waiting for the paperwork, marketing setup, etc. Should be in days, maybe a week.... You will not need to opt into beta. You will get the new app for free. The app will be titled 'Serious Sam Fusion 2017 (beta)' to signify that it's a preliminary release and that we will further update and fix it as needed. But it doesn't require opt-in."
If there's benchmarking support, I'll surely be running some Linux GPU/driver tests.