Is there an ultimate recourse for 2FA deactivation ? (entirely locked out of my account)

Bumping the thread for future readers in search of a definitive/authoritative answer on that question.

Dropbox support finally gave me an unambiguous answer, and it's a no.

They do not have a process for unlocking accounts if you lose all your means of access as described in my original post. So, if you do, you're done.

Excerpt from the exchange I had with them (translated from the original language):

"""

For security reasons, we can't disable 2FA for you because your email address isn't proof enough of your identity. If you can't use your 2FA code and don't know you recovery codes, we can't help you in accessing your dropbox account

"""

Note that there is still some wiggle room where they say "your email address isn't proof enough", when I told them I could provide much, much more proof of identity and ownership of the account, BUT it seems to me that their internal processes stop there when it comes to account recovery for reasons other than death of a user (see prior messages in this thread for details on that).