Why can't there be some project that can take static export of sites and serve them via torrent or IPFS https://github.com/ipfs/ipfs like system. Users who care about this stuff could then pool their bandwidth and storage to keep these things alive, if only in a static form for historical preservation.
how much could a bill like this possibly be per month ?
if people are so interested in keeping the forums, you could try to ask for donations ?
I would guess it's expensive enough to get cut, right? People could donate, sure. It would still need dedicated resources. It's a popular enough service to need high concurrency and reasonably high availability - at least for peak usage, like when the new trailer for the next great trilogy drops.