Nice episode. So nice I decided to join the forums here and make a comment.
Where have all the sci-fi gamers gone? To boardgames! Look at the BGG top 100 games and look at how many are sci-fi.
Where have all the sci-fi wargamers gone? To Fantasy Flight. Use the BGG Advanced Search and select 'Board Game Category - Science Fiction' and 'Board Game Subdomain - Wargames' and look at the (sad?) results. Sorted by BGG rank the Top 10 are Star Wars: X-Wing Minis, Star Wars: Armada, Nexus Ops, Space Empires 4X, Star Wars: X-Wing 2e, Battletech, Necromunda, Ogre: Pocket Edition, Star Trek: Attack Wing, and Risk 2210 AD. Definitely NOT a grognards list.
Welcome!
I'd agree that the list of currently-popular sci-fi games aren't very groggy, but consider a bunch of those are tied to current media licenses that started outside the grogosphere and had built-in audiences for them.
Moreover, I keep coming back to my comment about "OCS in space" - I don't know that you'd notice the difference btw a sci-fi OCS-style game, and Baltic Gap, just b/c at the level at which OCS operates there's too much aggregation of the 'cool stuff' to really notice it.
Look at the list of games you've got above - every one of them is a tactical-scale game with cool toys except 2: SE4x, from a wargaming company, and 2210, which is built on an existing franchise (and still has a high toy factor).
This is probably worth it's own discussion separate from the podcast threads, but the guys playing OCS and GCACW just don't seem terribly interested in space-ray shootouts (Ardwulf excepted, of course), and they guys looking for the sci-fi immersion of jetpacks and ion cannons aren't going to see those things in something at the OCS level.
And that's leaving aside any thoughts of being interested in specific historical periods over others.