As a practical matter, it doesn’t matter which party controls the Senate between now and the Inauguration. Because, believe it or not, they’ve skipped town and won’t be back until the Inauguration.
They had a ‘state work period’ scheduled, and they’re keeping it, no matter how much you’d think the events of yesterday might require some sort of Congressional response.
The House is also on vacation. They were originally scheduled to be in session through Friday and then have a ‘district work period’ until the Inauguration, but they cut short their session and have also skipped town.
And to clarify my point: it wasn’t that they necessarily do actually vote on who is majority leader. It’s more that, if there was some dispute over it, the only possible remedy would be a vote, and the majority would win and thus get to decide who is the majority leader–which means they dictate what comes to the floor.
It’s rather similar to the hypothetical talk about whether the Vice President could recognize someone other than the majority leader to be the first person to bring things to to floor. The majority would object, and then vote to say that the majority leader should be recognized first.
And that is essentially what the majority leader is as a role–the person who initially brings things to the floor, and the powers this grants them. The rest of their job is just as leader of their party in the Senate, and thus isn’t really different than the minority leader.