Everything under "The Future" really excites me, especially the geo-partitioning features. That is something that I'm really looking forward to be using!
If you have a marketing webpage, you might have a link to signup or login pages. If you can hijack the index page you'll also be able to hijack the links.
Even if you don't have signup or login pages, a MITM attacker can add them. Or they could add a "buy now!" link with a convenient entry form for the user's bank details. The relevant question isn't what your page has that's so important, but rather what an attacker could make it have that would cause trouble.
I get the distinct impression that they invested in good tooling, CI and CD, which probably enables all sorts of product engineering greatness. Hopefully it's a trend.
You could set up some "failover" upstreams that are mirrored using git's post-receive hooks. Or, you could define a particular git remote to have multiple URL's.
1: https://www.patreon.com/evanyou