Simillar to how Western WI used to be the most progressive part of the state. Columbia isn't a very big city for what it's worth; it just seems like a place Ds are on borrowed time on.
...what? Columbia is moving left, not right. It's a university city, and a lot of the characteristics that normally make state capitals D land in Columbia instead (which is why Jefferson City is so R). It has strong growth, and it's the "cool" place to move in Missouri (and has been for a while).
There is no place where Democrats are "on borrowed time" in Missouri. The time has run out, everywhere. There is nowhere to go but up.
Also, by "most progressive" I meant most culturally progressive, not most D. Bellefontaine Neighbors is where every single person is a Democrat, Columbia is where people ask for your pronouns when they meet you.
How much would the University of Missouri be affected by students not voting on campus this year?
Most college students aren't registered to vote at their college. The effect will be minimal.