President Biden couldn't have taken the oath of office on January 20, 2021 and said that he was only doing one term. Senator McConnell and his crew wouldn't have let him get anything done because he would have been a lame duck on day one.
The debate was probably the only hitch in his plan. IF the debate had gone well, nobody would have discussed or pushed for him to not run again. Like I've said before, I thought the NATO Summit was going to be his great swan song. Announcing after all the kudos. I'm glad he didn't announce it then.
This may have been a show to delay until after the Republicans had committed to their ticket. Convention ended on July 18. It's supposed to be hoopla about the Republican candidate...then, three days later, he steals the spotlight. Not too shabby. Timing is everything.