I don't think Steem needs this. Steemit already has multisig and 2FA only handles authorization. It would be better if Steemit made it easier to backup encrypted private keys or encrypted passwords on some distributed storage medium such as Storj.
But there probably wouldn't be much to gain from 2FA. Can you convince me why 2FA would do anything when multisig already exists?
Because once the keys are generated and stored on the user side, and likelihood of their compromising is much higher than the one-time code generated repeatedly by a certain algorithm.
I think that for secure all means are good, and service need provide users ability to use all of them, for example, in realization one project we using digital pin+ master password, two-factor authentication and multisig, and it really safe
Not only me raised the issue, it is therefore relevant
https://steemit.com/steemit/@blakemiles84/steemit-needs-two-factor-authentication
https://steemit.com/proposals/@thebatchman/supposedly-hacked-accounts-on-steemit-time-for-a-new-proposal#@mixa/re-thebatchman-supposedly-hacked-accounts-on-steemit-time-for-a-new-proposal-20160714t160009976z