It’s not so much drones that make it obsolete as it is that it won’t be long until they have unmanned tanks. The humans are surplusage, for the most part. You need a really heavy tank to protect soldiers, and that means it eats a lot of fuel. A remote vehicle needs less armor, less internal space, and could therefore be designed so as to save a lot of fuel.
You are going to protect soldiers from laser and arial attack with a Tank!
The ground war is obselete! No need for troops when the city and battleground is decimated and non existant!
As the General in this war there will be nothing left but scorched earth!
No puppies to bring home total oberliteration!
And you still need a Tank!
I doubt there will ever be an unmanned tank, unless perhaps for an urban environment. Anything unmanned would be too hard to drive over terrain.