Absolutely no one said that they need to replace all their legacy ports. Adding a couple of the small USB-C ports to the front and back is all that's needed on desktops. On laptops, putting one on each side should be doable.
A computer that you buy today will last 7-10 years. I guarantee that there will be lots of USB-C devices in 3 years.
A computer that you buy today will last 7-10 years. I guarantee that there will be lots of USB-C devices in 3 years.