Ask HN: Authenticator app with push notifications?

Today, I just saw an announcement by Google that they are releasing a feature for their Google Apps customers which allows users to receive a push notification on their phone for Multi Factor Authentication (MFA) [1].

For a long time now, I have been thinking about creating an app which would allow users to receive a push notification on their phone in order to provide the MFA code directly to their browser (via a browser plugin). It could work with any current site which requires a MFA code that can be generated from an authenticator app on your phone.

Would you use such an app? Would you pay monthly for the push notifications feature and for developers to maintain/add new site integrations? Why or why not?

Also, which authenticator app do you currently use and are you happy with it? Previously, I used the Google Authenticator app [2], but I recently started using Authy [3] and the UX is dramatically better IMO. I'm asking to get a sense of which features are important to developers who use these apps on a daily basis (AWS, GitHub, etc).

Thanks!

[1] https://googleappsupdates.blogspot.co.uk/2016/06/new-settings-for-2-step-verification.html

[2] https://support.google.com/accounts/answer/1066447?hl=en

[3] https://www.authy.com/app/