I got the exact same question is it possible to change Account Holder to another Apple ID ?
>Can I change the Team Agent/Account Holder Apple ID to my regular Apple ID that I'm using on my devices everyday?
In that example, you may want to use the 'Account' link above right, then 'Membership' on the left, then the link on the right 'Need to edit this information'?
It seems that you can still activate 2FA for your developer Apple ID on a device that you already use with another private Apple ID.
I asked the Apple Developer support the same question I was asking here. I'm posting their reply here since it will probably help many developers who are facing the same issue when Apple will soon require 2FA:
"Even though your apple device is connected to your private Apple ID, which has Two-Factor-Authentication already enabled, you will still be able to also set up Two-Factor-Authentication for your developer Apple ID with it.
For this you would have to log out of your private Apple ID account on your device for a few minutes and log on with your developer Apple ID. This only takes a few minutes.
To prevent data loss please make sure that all data on your private Apple ID is securely stored in the cloud. Alternatively you can perform a back-up before logging out.
After you have successfully switched to Two Factor Authentication for your developer Apple ID using your device, you can log out and then log in with your regular Apple ID again.
Security codes will be sent to your verified phone number in the future and you won’t have to log in with the developer Apple ID on your device again, if you don’t wish to do so."