There's no reason an independent entity couldn't spin up a new trust anchor, as long as they get RPs to follow it. If a government started meddling with an RIR's RPKI database, that would provide a pretty good set of incentives for an AltDB-but-for-RPKI TA to gain adoption. Even in the absence of meddling, this would be useful for legacy IPv4 holders, who currently don't have a way to participate in RPKI.

As a legacy IPv4 holder for over 30 years, I realize I'm going to be forced to pay ARIN at some point. It's been a good run though.