I protect my Twitter with Universal Second Factor (using a Yubikey). Does this mean Twitter will stop that feature and devolve to insecure SMS for paying member

I protect my Twitter with Universal Second Factor (using a Yubikey). Does this mean Twitter will stop that feature and devolve to insecure SMS for paying members? If that's the case, it should be called out at every instance. Account takeover attacks are no laughing matter. They can defame people and cause a lot of damage. Yubikeys/U2F should be the de facto standard for 2FA, and that feature should be for free at all times. 'Everyone deserves good security'.