No.
He fits the meta a lot better then other champions that need the changes, He really isn't fun to play against at all, and so what if the River is off limits?
He has the rest of the map to place shrooms.
His Q is still devastating to AA reliant champions, which are in pretty much every game.
His AP scalings are rather high, and shrooms can literally win games, team fights, objectives and so on.
And you mention counters to his shrooms being a sweeping lense, as if that was a counter to someone laning? Who the hell goes into lane without a yellow trinket early on? And that still requires they land it in the right spot and manage to destroy them, Which you can Q to stop.
A ranged squishy top laner in a era where top laners can do wolves easily
He isn't the only ranged squishy that does top lane, and it isn't a weakness considering he is still ranged. And if a top laner is doing wolves the jungler is going to be pissed since most junglers take wolves on the first clear.
In a world where gnar exists, and , in lane, has the same purpose, but becomes a monster of CC and high base damage on teamfights, why would you EVER pick teemo?
What the hell does Gnar have to do with this? They are completely different roles? But to enlighten you, Teemo is for map control, and being an anti adc/fighter. Gnar has is like a pseudo tank carry thing.
This isn't to say Teemo doesn't need to be changed, because he does. His kit is a mess of different things, he isn't fun to play against and doesn't fit the meta as well as he could. But he is LOW LOW LOW priority for champions that need to be updated then he does.