I agree that it would be nice to have python add-ins in Pro (since I have them already written for desktop), and I'm holding out for them adding the functionality in the future. Part of the issue will be with Pro having the "ribbon" style so they would have to figure out how we can access that interface.
One workaround is that you can still access and run the tools if they are in a custom toolbox. So, if you connect/add that to the new "catalog" in Pro, it should still work (pending any other changes that need to be made to the code for the Python 3.4). Not a perfect solution, but at least for me the programming and organization part isn't wasted. And for me, at least on some initial test (a while back in beta...before Python 3.4) the speed performance was so much faster with the 64-bit Pro that for some of my processes, I will live with it.