I don’t think anything has yet officially been confirmed. However, the 221s are pretty much the only suitable option to cover the timetable, with the ongoing rolling stock issues.
All of the 222s are supposed to be gone from EMR by the end of the year. With the 810s, who knows how long it’ll take to fix them, as well as how complex all of their issues are.
We don’t know how long the revised timetable will last for, either.
A lot of questions but not a lot of answers. Though I’m sure as time goes on, things will become clearer.