This. Math proofs are useless in 99.99% of situations because they are far too expensive to actually use in production. Only something like AWS would use formal proofs to verify some system property for reliability.

With some super-math Q* bot, a mathematician could presumably create actual proofs/simplifications for complex real world problems/systems at very affordable time and costs (in weeks not years).

The mathematician in this case is far less skilled than the bot, but that doesn't detract from their market value. Most programmers are way less skilled/smart than the library authors that they rely on, that doesn't stop them from earning $$$, because they are useful.

There's a massive corpus of useful math proofs, just most of them have been implemented and are second nature now

I don't think it's true that "math departments have been closing for a while now"

Correct - math departments are doing fine. Not quite as fine as CS departments, which get showered with piles of money and their grad students poached to make money in industry. But so long as other university departments want their students to know some combination of calculus, linear algebra, and statistics, math departments will continue humming along.

It's an impression I had, I don't know any hard data. For example:

https://www.reddit.com/r/math/comments/l7yyir/not_joking_uni...

https://www.reddit.com/r/math/comments/15of64l/rumor_west_vi...

I think it's a very unfair assessment to make from these two examples. I think it's like saying Silicon Valley has been shutting down for a while and providing two examples of startups. I will say from my personal impression as someone in pure math, I disagree with this statement.

I don't know what "fair" has to do with that. These are two examples that caught my attention, and I might be wrong that this constitutes a trend. If you have data that says otherwise, please share.

I think the funding in pure math is not going down in recent years. Nor are math departments much smaller than they were say ten years ago. Otherwise I'm sure how best to give evidence of math departments not shutting down! Do I list healthy math departments?

I guess this would be a case of applied math ;-)

Joking aside, of course it is not on you to provide evidence. I would probably start with seeing how many universities have pure math departments over a time axis from now back to 2000 or so.

It might even be that the total funding increases, but is more centralised in the big universities. So a total funding timeline would also be good.