Allow me this hypothetical:
A compilation of the top Senate projections for 2020 give the Republicans 50 seats, the Democrats 46, and have 4 rated as true toss-ups (Maine, Arizona, Colorado, and North Carolina). If the Romney caucus defected, that would take the Republicans to 48 and the Democrats to 45. So for Mitch McConnell to remain as majority leader, the Republicans would need to win two of those four states and the presidency—or three of those states while losing the presidency. For Schumer to take the gavel the Democrats would need to sweep all four states, pick up an additional seat somewhere like Georgia, and win the White House.
That leaves a not insignificant statistical window where the Romney/Murkowski/Manchin caucus could have the power to negotiate over who is majority leader, make real changes to how the Senate operates and the floor agenda, and have an absolutely critical oversight role should the grim prospect of an unbound Donald Trump serving a second term come to life. That seems much more interesting to me than furtively liking George Conway tweets.