The Star Frontiers fan community deserves a reward for their loyalty IMO. Even a straight physical reprint would be appreciated, I think. Maybe you skip the dice and crayon, but the maps and counters are mandatory, they're part of the charm.
A modernized version that mashed up the mechanics of AD, KH, and Zebulon's Guide could work as well, the nostalgia factor is strong with that game.
Alternity's fine (and the settings were great) but I'm not sure it'd sell to more folks than Star Frontiers and it would be facing off against more modern designs like Cepheus without as much nostalgia power behind it as older games that lasted longer. OTOH, it would be cheaper to do reprints of without the (relatively) complex components shoved in all the TSR boxed set games. Something to be said for simple hardcovers and a few modules.
Much as it pains me, I can't see anything else in their back catalog that would be feasible to do a revival in the face of modern designs competing for the same niches. Prohibition gangsters, gonzo post-apoc on or off a generation ship, espionage, Wild West, Conan, even Indiana Jones style adventures - there's already perfectly good options out there, and I don't think any of the TSR versions have the quality or nostalgia appeal to be worth doing without being rewritten so heavily they'd be ghosts of their old selves.
Of course, if anyone wants to champion a new edition of Rocky & Bullwinkle (complete with hand puppets) I've love to hear the reasoning. Sheer irony value, maybe?
Things on my "Nope" list for various reasons:
No Empire of the Petal Throne unless there's no way at all for anyone connected to Barker to profit from it. WotC probably doesn't have the rights anyway.
Similarly, Buck Rogers XXVC would be a pretty strong peer to Alternity or Star Frontiers, but the IP rights for Buck are tied up with Lorraine Williams' family (hence her fascination with forcing TSR to use it) and I think most folks would rather not give them more money. There are already versions with the serial numbers filed off floating around fringes of the OSR community anyway.
Marvel Super Heroes stuff would be a huge draw for many people but let's be serious, that license would cost a fortune and either be hopelessly outdated (for a reprint) or almost unrecognizable (for a updated version that covered modern Marvel) - and of course Marvel has an RPG at the moment, for better or worse.
Dragonquest. I hate the old versions of the game (really math heavy). But would like to see a new take on it.
I'm as much of a fan of SPI as anyone, but the game barely had a setting, and if you didn't like the mechanics (which is what the surviving fan base seems to love about it) I don't understand the appeal. What am I missing?
Heck, they've probably got the rights to Universe too, and that had more published setting material than DQ thanks to Ares with about equally clunky mechanics.
Didn't they acquire the New Infinities stuff? So, Cyborg Commando.
News to me if they did. They company was forced into bankruptcy by its own investors trying to get some kind of money back, and AFAIK the only way WotC could have ended up with CC would be buying it during the asset sale. Most of the company's value came from the Gord books during its lifetime, and I wouldn't be shocked if the alt-universe Traveller novel trilogy was the second most profitable thing that got to print. CC was a legendary flop, and I don't think I've ever heard who wound up with the rights when the dust settled.