The principle of "spread across multiple platforms" is fundamentally inconsistent with a "safest holdout".
You need to hedge your bets.
You need to realise that free services can be discontinued, paid contracts can be terminated, content or accounts can be flagged, copyright or patent claims may be asserted (more the former than the latter, generally, but expect patent claims on more capable systems), domains may be hijacked or squatted, and self-hosted systems may be DDoSed, require ongoing maintenance, moderation (if user / third-party content is permitted), etc.
POSSE -- Publish on your own site, syndicate elsewhere -- is probable the most robust option overall.
Yes, what I've been saying is that we're moving back to where we were 20 years ago. We're moving back to a hosting model where you can not completely rely on any hosting company to get the job done.
Big tech companies changed things a lot, and developed very sophisticated infrastructure that we could not compete with.
Nobody could compete with YouTube for awhile. But now, YouTube has made itself so unreliable, that people are forced to find new video hosting services, and people will put up with slower speeds for more reliability.
> We're moving back to a hosting model where you can not completely rely on any hosting company to get the job done.
That's become my mantra about anonymization: that you can't trust any one system/provider, so it's prudent to distribute trust. Basically, what Chaum said, so many years ago.
But that's harder with hosting. Sure, if you lease a domain, you can easily point to different IPs. But then, what happens if you lose the domain?
And for people who don't lease domains, how will your followers find your other sites? Once the one they were hitting is gone, I mean. Some will bookmark all of them, for sure. But not most, I bet. Search services would help, but I suspect that'd be iffy.
This is exactly how I've been treating GitHub lately; in addition to my own SSH-enabled server, I have both GitHub and Bitbucket configured as remotes (strongly considering adding sr.ht to the mix), and every push pushes to all remotes simultaneously (well, technically sequentially, I guess).
OK, so what's the safest holdout?