Add support for Yubikey U2F authentication via a security key. This would be a big selling point to enterprise customers who are rightfully very concerned about web security at the moment. Many have been bitten one too many times by Wordpress security breaches, so being able to show that extra level of security beyond 2FA authenticator app would be huge. 

Also being able to "enforce 2FA" for members of your team account would be a major plus. ie. cannot join team until you have enabled 2FA on your account.

https://blogs.dropbox.com/dropbox/2015/08/u2f-security-keys/

https://www.yubico.com/works-with-yubikey/partners/