Just noticed this blog post from Fabian Steeg on the value of personal domain names:
So the mere decision to use a custom domain for my blog many years ago made it independent of the actual hosting location (wordpress.com or self-hosted) and publishing system (wordpress or my own software). In a way I’ve been referencing a system for years that I only now created. Your own domain and URLs really give you a lot of control over your content, even if that content is actually stored elsewhere for years.
Strongly agree with this. Having your own domain will future-proof everything you publish.