I guess if I was a video editor I’d feel a little betrayed since it’s clear FCPx doesn’t have a lot of features pros need to do their jobs. If Adobe did something similar with After Effects I’d cry my eyes out.
It looks like Motion 5 has much more integration with FCPx as far as publishing animated elements (and even effects) and being able to easily switch back and forth between the applications. This would be good for people familiar with both applications and give FCPx users more flexibility with Motion 5 templates. The user base for FCPx and Motion 5 may get a lot bigger since it’s so affordable. Offering Motion 5 templates on VH might be a good idea but only if the (quality) Author base is there.
I created a template in Motion 4 that is being sold on the other template site and I guess it’s doing ok sales-wise. My intention was to create more Motion templates but I just never put in the effort because I’m so comfortable with AE (my BFF). However, Motion was VERY easy to learn and intuitive, so I may need to widen my social circle a bit more 
I’m definitely considering upgrading Motion, if only I could clone myself so I can do AE at the same time!