I use my tablet to supplement my desktop and vice versa. Most tablets these days could replace other form factors for light duty computing. But the MS tablets are still lacking the CPU/gpu power to truly replace a desktop gaming machine, not to mention, most tablets aren't exactly user friendly when it comes to upgrading hardware.
In the near term, no, I can't see the surface pro replacing towers. laptops, maybe, but it'll be 5-7 years before these are powerfull enough to make me think twice about getting rid of my tower. And even then, the desktops will have increased in power enough to warrant them staying in use for serious gamers.
CPU: Ryzen 1700 GPU: MSI R9 480 4GB
RAM: 16gb DDR4 Disk: 128SSD + 2x1TB
Power: 750w asus prime b350m-a uatx mobo