EDIT: or if public universities ran their own instances? All content submitted by users would be CC licensed.
EDIT EDIT: To keep costs down, just rate limit the number of posts that could be made per user.
Or is this just their own instance where nobody else can participate?
Not that they can be replaced with RSS, but a lot of use seems nearly just that.
The fly in the ointment is DDOS protection. That might not be a problem in some cases, but once you attract enough attention you become a peachy target.
I could see a university hosting a Mastodon instance for their own students, though. Moderation is probably a little easier if you have the person’s real name.