If the fee was sufficiently high (one time $250-500?), I think it would be a sufficient filter that most non-serious proposals would go away, and the orgs that really need to be on this list would get on it. It would be pretty easy to just refund the amount if the proposal was rejected, and I don't think it would have to happen very often. Could be as simple as a Stripe form and a single member LLC that files as a schedule c with a 1099-k every year if one person wanted to own that maintenance.
I'm sure someone will gawk at this idea/amount but look at the legitimate users of the PSL.. Google, Github, root domains that fork over $500k to ICANN, governments that spend $25k on hammers, web hosting services for third parties (Neocities, Netlify, etc), cloud hosting proxies for consumer NAS, et cetera, which more often than not will be running their own BGP and IPs to deal with abuse complaints (our ARIN annual renewal alone is $600/yr). Let's be honest here, any organization that can't afford a Valentine's Day dinner for 2 probably shouldn't be hosting content for untrustable third parties, and probably shouldn't be on this list. Users of this list are going to be high value orgs that have the means to pay for its maintenance, and I do think it is a privilege to be added to this list that comes with at least the responsibility of supporting its maintenance.
There's a lot of low grade junk and dead sites on the list as-is, which may also need to be dealt with after their domains expire and the new domain owners discover their subdomain cookies don't work, and every single browser on the planet gets a performance hit sifting through that extra junk every time a request is made. Then you get the opportunists coming in and trying to use PSL to scam something (I'm going to avoid reading how that works this morning because it sounds headache inducing to me)
Aside from just being a really nice filter to keep maintenance time reasonable and reduce junk, the maintainer(s?) of this list are hard working professionals that deserve to be compensated for their time spent on it. I've long been an advocate for removing the "free beer" component of free software, especially when dealing almost exclusively with organizations that have the means to support that.
There is certainly a possibility that the browser people will push back on the idea, but I think given the alternative of having to maintain the list themselves with overworked staff and deal with all the crap just so they can punch down on an OSS maintainer, they would instead appreciate the increase in speed and quality and go along with the change, rather than fork it into an unmaintainable mess. But if they did do that, I also think it would be fine for y'all to just say "you know what forget it, I'm done sacrificing my valuable time" and move on. It would be nice if browser orgs contributed to maintenance here too, but I don't see an easy way to incentivize that for them, it seems easiest to just schedule fees for changes to the list itself.
Not trying to start a revolution here or tell anyone what to do, just adding my thoughts, and of course it's easier to write an email than actually implement any of this, but I hope this at least lays some support down and some arguments here for that support. Cheers!