He defines the direction yes, but inertia also matters. Twitter may be small by Facebook standards but it's still one of the largest social medias in the world. If you grab the wheel of a giant ship moving full speed forward in a given direction, you may want to set direction, but it'll take you time to steer it in that direction.
In 5 years Twitter will be absolutely nothing like what it was a year ago. But we're still in a transitionary period that's merely starting.
I don't think inertia matters. Even if the users don't change a bit compared to before the take-over, the network still moves to the right if people are constantly being shown right-wing tweets and pushed into right-wing topics. That doesn't take 5 years, it takes one day. And that day has passed a couple of month ago.
And since then Musk has been banning people on the left and un-banning people on the right, so the users definitely have changed already.
In 5 years Twitter will be absolutely nothing like what it was a year ago. But we're still in a transitionary period that's merely starting.