The account will never vanish once the process completes. The ability to login directly will be removed. So logging into the website will likely just send you over to the transfer page to create a jagex account, or log into an existing to import it over.
The game will have the old login portal disabled and require going through the launcher.
They'll never make it so you just lose it, people come back to the game after years and need a way to import over to continue playing. Wont be any different for active players with alts needing to convert over.
2FA authentication is mandatory on Jagex Accounts, you cannot disable it at all. You'll either have the email method, or the code generator + backup codes, or both. Accounts will never be accessible without one of those 2 methods.
Can I turn in a paper without citing all sources?
"No."[1]
1. William Shakespeare,
Hamlet
, Act III, Scene 1, line 96.
30-Jun-2023 14:53:06