On the very informative Train World video yesterday evening I asked if the Cab2 would need any upgrades to work with the Base3. Dave responded and said that in fact, V1.7 has some enhancements to work with Cab3 which he did not elaborate on. While previous versions, not sure he said specifically how previous will work with Base3, he did say that V1.7 has Base3 specific programming.
As of now there are no further planned updates for Cab2 past V1.7.
My suggestion to all who are planning to get Base3, and Train World said they are getting a ton of pre-orders, I would get your Cab2 updated to V1.7. Lots of good information on the Base3 from Dave on the program. Thanks Train World!