3rd-party PHEV systems in 2010 Prius?

Here was my fantasy:

The day the 2010 Prius was announced, Hymotion would announce that they had been working with Toyota on the 2010 Prius. They would announce that the L5 battery would be immediately available for the 2010 Prius, because Toyota has made only very minor physical, electrical and computer changes.

Plus, with the new stronger electrical motor, the car would accelerate faster without turning on the ICE. New programming and user buttons would allow electric-only operation until 55mph.

Sigh. Of course I knew it wouldn't happen. What's more likely:

Hymotion doesn't get a 2010 Prius, or enough information to make the L5 work in it, until we do. The physical area looks roughly the same, but there are probably significant computer changes. The electrical motor appears to have a little more horsepower, but a LOT less torque. There is an "electric only" button, but I've not seen any word about limitations.

I kind of suspect the 2010 Prius is not going to significantly better than the old ones. Why would it? Toyota may well make changes, including a better electric motor, when THEY install lithium battery packs. But there's probably no incentive for them to help out 3rd-party vendors.

Anybody know more about this, or have other thoughts?