virtualbox.org

I am running virtualbox 5.1.30 and when I click "Check for updates" it tells me that I am on the latest release.
Why doesn't it tell me about the 5.2.2 release?

Because the update funcion checks only for the current branch. And 5.1.x != 5.2.x.

Ah ok, I See.
Does that mean that if there are no further updates to the 5.1.x branch then even in 5 years time the "check for updates" mechanism will still say that I am running the most recent version?

I don't think anyone can tell you how the software will work in 5 years time.