You seem to have the false notion that corporate distros are safe (or something). But, that's not true. Look e.g. at the demise of Clear Linux OS.

For (perhaps) a better assessment on whether a distro is well-established^[I.e. that it will not cease existing overnight.] or not, consider looking at the following factors:

• How long does it exist? Like, if it's old enough to drink, then that's definitely a good indication.
• How strong is its community? If there are literally millions of users, many of which actively contribute, then that's definitely a good thing.
• How active is its development? The Linux landscape is constantly evolving. Hence, adopting changes (or, at least, enabling them) is somewhat to be expected.
• Does it serve a distinct raison d'être? It simply has to offer a strong justification for its existence.
• Does it have any strong dependencies/contingencies? Here, a lack thereof is actually what's good.

TL;DR: If you want to be absolutely safe, then I'd recommend Arch, Debian or Gentoo.