I don't get it. What's TSR really worth these days without D&D that anyone should spend real money to buy it?
Say you could kickstart Star Frontiers and maybe Top Secret S/I, or who knows Buck Rogers in the 25th Century - how long would that last beyond the initial nostalgia burst?
Star Frontiers and Top Secret have some nostalgia value for some older gamers, but neither game had strongly defined settings.
Top Secret was pretty generic spy genre fare . . . and the current Top Secret game from Solarian (formerly TSR2) has no connection to the original game in either rules or setting (although both games share the lead designer, Merle Rasmussen). Then again, there isn't much there to "share" if Solarian licensed the original game from WotC, it wouldn't be worth it! The only value is the nostalgia factor on the name itself, which is limited.
A new Star Frontiers would be similar. It wouldn't be worth licensing the original game/setting from WotC, the only thing worthwhile is the name . . . and again with limited appeal beyond the OSR crowd.
Buck Rogers though . . . the TSR version of that setting was well defined and had some depth to it! However, while Buck himself should be in the public domain (it's apparently somewhat complicated), trying to revise the TSR-era setting would require a license from both WotC AND the Dille Trust (the holders of Buck Rogers IP). That's not likely to happen. Although, there are rumors a new version of Buck Rogers is in development in Hollywood . . . .
The only classic TSR-era RPGs worth licensing are D&D and Gamma World. Even Gamma World is iffy, as it has the same problems as Top Secret and Star Frontiers, although with more attempts to revitalize it over the years. Same with Boot Hill and Gangbusters. All of these games outside of D&D itself have only a limited appeal to the OSR crowd, and none of them have a lot of depth to them to distinguish them from their respective genres.
Now . . . if WotC themselves (perhaps with a licensing partner) decided to try a new Gamma World or Star Frontiers based on the D&D 5E engine, with a modern-style reimagining of the settings . . . I could go for that!