We're never going to be able to have everyone use two factor authentication
Every so often I think about two-factor authentication here or talk to people about it. In the process of doing this, I've come around to an important realization:
We're never going to be able to have all our users use two factor authentication.
The largest fundamental issue is cost. If we require universal two factor authentication, the department needs to provide 2FA tokens to everyone (and then manage them, of course). Current typical prices are $50 US one time costs plus we pay for all management, or $33/year (and someone else worries about management). At that cost level, we're looking at tens of thousands of dollars of cost. The budget for that is simply not there. Even with probably unpopular moves like charging graduate students a '2FA token deposit' or the like, we still have a not insignificant population that the department would have to cover the costs for directly (either directly out of base budget or by forcing professors to pay for postdocs, visitors, etc who are associated with them).
(We cannot assume that all people have smartphones, either, and delegate our 2FA authentication to smartphone apps.)
I presented this as a pure cost issue, but of course it's more than that; it's a cost versus benefits tradeoff here. If we were guarding extremely important data or systems it might be a cost that the department either was willing to incur or had no choice about, but the blunt reality is that we're not. And in practice moving everyone to 2FA would provide only a modest increase in security over what we currently have, since (as far as we know) account credentials are not getting compromised left and right. With high expenses and only a modest security increase, the tradeoff is not in favour of universal 2FA.
This doesn't mean that we'll never have any 2FA. Instead, what it means is that any two factor authentication deployment is going to be a selective one, where some accounts will be protected by it but many others won't be. A selective deployment puts various constraints on what software we can use and how we can deploy things. It also suggests that we may want to be able to use more than one 2FA system. Some people are likely to already have central university-issued 2FA tokens, some people will have smartphones that they can use for 2FA, and some people may have locally purchased 2FA tokens like Yubikeys. It would be good if we could accommodate them all, although this may not be realistic for various reasons.