You don't need to replace them, just get different cables, type-c is still USB and also happens to be thunderport so you get DisplayPort as well.

No need for a dongle for your DisplayPort monitor, just get a DP->USB-C cable, done, I'm running a 4k monitor at 60hz this way.

Same for your hard drive, it is probably micro-usb on the other side, just get a micro-USB to USB-C.

etc.. etc..

You don't need new stuff, just new cables, which is annoying but not anywhere near as bad. Protocol is the same, just a different shape.