And if I loose for some reason access to my phone number, termination of current number to create a new line with a new phone, I loose access to Gmail forever ?
Possibly. Security has made internet enabled accounts outright user hostile. Try helping a 70 year old guy get into his Gmail again. I despair over the disrespect Google and the other major internet corps show their tech-naive users.
I've heard "I'll call them" far too often, and am perpetually forced to share the bad news.