Companies are already using on-premise GitHub server, if they are using GitHub in the first place. There are many other self hosted solutions which are quite common in enterprise environment.

In my experience companies are moving into GitHub for Copilot and GHA.

GHA maybe, but copilot is just another mid tier player in a congested space.

Doesn't stop folks from wanting to buy the MS brand. Execs are really out of touch these days.

It's a cheap mid tier player. You get more tokens per dollar.

What kind of alternatives do you see as viable for large(ish) commercial users?

GitHub on-prem. Officially called GitHub Enterprise Server. You can have GitHub, but hosted on your own servers.

So you still pay them, you do the hosting work, and you get a product with worse features than gitlab?

Yeah, at that point why would anyone choose GitHub?

And it costs you more money than GitLab.

but you can be smug when theres a github incident, and thats hard to put a price on

You can do that with gitlab.