So, there are a whole bunch of interesting ideas here, but…
It’s a huge, all-or-nothing proposition. You have to adopt the language, the source control, and figure out the hosting of it, all at once. If you don’t like one thing in the whole stack, you’re stuck. So, I suspect all those interesting ideas will not go anywhere (at least directly; maybe they get incorporated elsewhere).
You can gradually adopt Unison, it's not all or nothing. It's true that when programming in Unison, you use Unison's tooling (which is seriously one of the best things about it), but there are lightweight ways of integrating with existing systems and services and that is definitely the intent.
We ourselves make use of this sort of thing since (for instance) Unison Cloud is implemented mostly in Unison but uses Haskell for a few things.
There can be enormous value in creating multiple pieces of tech all designed to work really well together. We've done that for Unison where it made sense while also keeping an eye on ease of integration with other tech.
I think that the messaging around this is going to be pretty important in heading off gut-reaction "it's all or nothing locked in to their world" first takes. It's probably attractive marketing for things to be aimed at "look how easy it easy to use our entire ecosystem", but there's a risk to that too.
While I'm sure the creators would love to see their work become commercially successful and widespread, I don't think that a very interesting criteria to judge what's essentially cool computer science research.
It’s a huge, all-or-nothing proposition. You have to adopt the language, the source control, and figure out the hosting of it, all at once. If you don’t like one thing in the whole stack, you’re stuck. So, I suspect all those interesting ideas will not go anywhere (at least directly; maybe they get incorporated elsewhere).