I’m a bit skeptical on the first bullet point: while I’m all for an amendment to the US constitution that spells out in detail the limits on presidential authority, it’s still an amendment that has to get passed. That means that it needs a 2/3rds majority in both the House and the Senate, or it needs to be supported by 2/3rds of the state legislatures. I don’t think there’s any way in hell that Biden’s going to be able to get that through while the prospect of Trump regaining the presidency is on the horizon. At the moment, 47% of the US Senate is Democrat, with 4% caucusing with the Democrats most of the time, 49% of the US House is Democrat, and 46% of State Governors are Democrat. While it’s not 100% certain that all Republicans would vote along party lines, I’m reasonably certain that all Republicans would vote along party lines, which means a constitutional amendment is dead in the water.
Now, if Harris wins the presidency, there’s a good chance that the Republicans would be willing to vote for an amendment to curtail presidential authority. But right now? Nuh uh. Not gonna happen. As for the other two bullet points, they’re certainly more possible right now than a constitutional amendment, but still unlikely. Dems don’t have a filibuster-proof majority in the Senate, and I’m certain that the Republicans would filibuster the shit out of that. Even if that wasn’t the case, there’s no way it’d pass the House. Best case scenario, Harris wins, with a large majority in both houses, and is able to push some legislation along these lines through.
Edit: changed language from “ratified by 2/3rds of the states” to “supported by 2/3rds of the state legislatures”.