Except for devices which have a hardwired cable, you can get USB-C to USB-whatever and nearly all, if not all, professional equipment I know of does not have hardwired cables. So in the worst case, you need to replace your cables and in the best case, you now have four direct ports, more than any portable Mac has had since the transition to USB-C. And for the cases where the connection must be USB-A adapters are small and reliable.
If you haven't used a USB-C/Thunderbolt-3 notebook, being able to go from portable to charging, full size monitor, peripherals, external storage, etc. with one cable is a welcome change.
Apple's commitment to supporting legacy ports (albeit through adapters) is pretty good, in my experience. As an anecdote, I needed to get some data off of an old Firewire 400 hard drive and linked Thunderbolt 3 to Thunderbolt 2, Thunderbolt 2 to Firewire 800, Firewire 800 to 400 cable into the drive and it mounts like it would on a direct connection.
If you haven't used a USB-C/Thunderbolt-3 notebook, being able to go from portable to charging, full size monitor, peripherals, external storage, etc. with one cable is a welcome change.
Apple's commitment to supporting legacy ports (albeit through adapters) is pretty good, in my experience. As an anecdote, I needed to get some data off of an old Firewire 400 hard drive and linked Thunderbolt 3 to Thunderbolt 2, Thunderbolt 2 to Firewire 800, Firewire 800 to 400 cable into the drive and it mounts like it would on a direct connection.