@mmn Uh, sorry, after checking the help pages, I'm reminded there is no real account recovery since everything is tied to the phone number. So yeah, if you lose control of the number you can be impersonated, provided your contacts accept the changed safety number.
https://support.whispersystems.org/hc/en-us/articles/212535908
https://support.whispersystems.org/hc/en-us/articles/115005335227