This is a weird line to argue from... What guarantees any platform you use (yes, even including wordpress) won't delete you data or terminate your service agreement? Even more laughable, if it was unfairly terminated, how can you argue when you are dead?
If you want longevity -- and want a VPS, just load up your vps (in the case of DO) wallet, pre-purchase out your domain name for a few years in advance and sit back. That's the best you are going to get, without paying somebody specifically. If you are popular enough, your stuff will be archived anyway.
But for heavens sake, if you actually have a need for post-life longevity for your content, put it in a will. Plan for death.
