2 things: It makes sense if Festool is Tanos' largest "client", then product direction could be driven by them.
In regards to the front handle not laying completely closed when stacked due to the T-Loc lock... From that photo, it looks as if the Systainer3 T-Loc lock, because of its slight design change in shape, doesn't prevent the handle from being in the closed position when stacked. So I went and measured it, and the new T-Loc lock is not as wide. So when rotated, I can see how it will not be a problem.
Lastly, I did confirm the old and new locks are interchangeable. While not ideal ($$$), if it does bother you, you can replace the old locks with the newer style, if and when available from Festool.