As I understand it the Mana and Shiver were both designed in a modular fashion that would help minimize retooling to change CCs across models and years - similar to the ubiquitous small block chevy engines of the 50s - 80s.
As for a radical change to the Mana's purpose... that only makes sense if they're going to drop the current Mana model in favor of a new power train. The bike has other features that are very cool - and could be adopted elsewhere - but changing the power train would mean it's not a Mana any more.
On the other hand, they sold like 3 of them worldwide so maybe they may, some time in the future, want to re-use the other cool features in a more traditional platform.
The Mana and Shiver engines share nothing in common at all. They are completely different. The Mana engine is out of a large displacement Scooter and the Shiver shares design with the motorcycles. Two different animals al together.
You may be surprised to see how many Manas were sold. Maybe not in your part of the country but certainly in other places they sold fairly well.