What I'm most interested in is how they handle transition into whatever succeeds Type-C.

I'm not sure how effective is this going to be. Given the development in charging capabilities and bandwidth, people would continue buying new adapters and hubs/ port multipliers anyway. Yes, if a device ships with a basic adapter and you have to buy a better adapter separately, that is potential waste. Same goes for larger deployments where you want to use multi-port adapters (like charging 20 iPads at a time). As a user, what I appreciate is the convenience of interoperability. It won't necessarily decrease the number of chargers that I buy (= the amount of eventual waste). But it can decrease the number of chargers that I carry. Every time I bought a device without a bundled charger, I bought a charger for it anyway. And when I sell them, I sell them with adapters. I don't keep old adapters around. They have a lifespan. There are compatibility issues outside of port. As long as they are electrically compatible, a cable can sort out a different port. It's the electrical and protocol compatibility that really matters. Or you might end up with a 100 W nominal charger that charges at 5 W.