It becomes a case of do you disconnect and bring the TB 3 dock with you, buy a second 'traveling' dock or get just what you need for travel and hope for the best.
Honestly, I think a docking situation like that looks awesome. I like the idea of just usb-c, but Apple was probably a bit ahead of the curve here. In a year no one will be talking about it, and places like monoprice will have cheap dongles.
I also get what Apple is trying to do. My current MBP has the sd-card reader. I use it because I have a d7100, but everyone else I know with a mbp has literally never used that reader. For them it's a complete waste of space/weight. It is easy to get caught up in what we (as in HNers) need, and miss the fact that many people probably never using anything beyond the power port.
It's a similar situation with the removal of the headphone jack. Apple has stats and those show that the majority of people either use the headphones that come with the phone or have bought BT ones. Apple got ripped hard, but the rumors are most of the flagships coming out next year will also not have a headphone jack.
It becomes a case of do you disconnect and bring the TB 3 dock with you, buy a second 'traveling' dock or get just what you need for travel and hope for the best.