There have been no carveouts announced for SSO. I am migrating as many of my accounts on other websites as I can off of Twitter SSO because it seems likely to me that they'll stop working and I'd lose access to those accounts if I am not proactive.
Thankfully a lot of those sites will still have your email address so you can bet a ton of places will be emailing people asking them to update their accounts this coming week.
They are clarifying that it should not affect SSO, but games relying on Twitter SSO are already moving towards deprecating it for fear.