No drones won't be the frontline. You cannot use drones to physically hold an area, and they can be rendered useless in inclement weather or by signal jammers.

Not to mention, if you need to actually clear houses out like the U.S. did in Fallujah, you would needs tens of thousands of men. No amount of drones would suffice to replace them for this task.

And yes. People have been saying the tank is obsolete in almost every conflict it has fought in. Including the Russian invasion of Ukraine.

The drone has not made anything obsolete, but it has changed how effectively you can use soldiers and equipment.