Looks like Pavel and Scott got it all. I do not have any additions but will add to the custom DSDL importance point.
The new super generic definitions are hopefully going to be very nice to use for Plug and Play applications, when you just want things to work smooth out of the box. For applications with specialized demands: Where perhaps bus efficiency is of the essence, where data need to be synchronized, etc. They’re not going to be ideal.
Using Uavcan with custom DSDL needs to be a first class use case. It also means that manufacturers should have the opportunity to create custom types for their equipment (also supporting the generic types) and let users onfigure the generic or the custom types on a subject. This means that we need to start thinking about things such as namespace reservation in the near future.