I thought about something like this a while ago. I am all for expanding the community and working with RPi enthusiasts (we aren't all that different in many ways, and surely some people already fall into both camps).
There are a couple potential downsides , such as the cost for the Pyra stuff to go along with the RPi. One product is rather expensive since it has such a small following, while the other has a large community because it is so inexpensive. Despite that, it would give the Pi fans a way to have a mobile and fully featured way to use their RPi anywhere.
I don't know how many people would be interested in a Pyra with a Raspberry Pi as the brain. If it is still somewhat pricey people will want the best value for their money, and will go with the top model offered. For it to sell well I think it would need to be a significant discount over an actual Pyra. It might work out, I just don't know how much ED would lose by doing that. If it is a purely Raspberry Pi branded product, manufactured and sold by them (and inexpensive) it could be enough to kill off the Pyra.
I would love people to experiment and share what they come up with. Maybe if it isn't a finished product someone can share their instructions on how to hack together a Raspberry Pyra (which is far more believable than a certain KS that is currently going on).