I think it would be utter folly, leaving aside the current catastrophe, WoTC continues to use the TSR trademark on reprints of TSR era on DMsGuild, so WoTC are, as far as I can tell, using that trademark in the TTRPG space.
As far I can see, this gives WoTC a string case to litigate against a competitor and why would any potential games company want the risk. Most of these companies have a brand as strong as TSR at this point in time.
Even, if (nu)TSR had not flamed out so spectacularly, even if they had a product, I would have been dubious on their choice of name.
You might be right, from a legal perspective. I was wondering about that myself. If a trademark is no longer registered, but the copyright holder is still producing legacy PDFs with that name, that does seem pretty dicey, if brought to court. A trademark expert could probably say up front whether it would work. I simply don't know how important (or not) is the fact whether it's registered.
Nevertheless, I'd still like to see somebody with some monetary resources, and a deep love of TRPG history, form a venture which brings a bunch of old school IPs into a shared multiverse, with a shared rules system (even if dual-statted).