Since you mention the Bullet engine, do you plan to continue this as a simulation for Maya (basically exchanging the simulation engine behind it) or as a possibility to create your PhysX objects with Maya, too?
For me, I'm mainly interested in the second part.
I'm mainly interested in having a free physics authoring plugin for Maya available. The current COLLADA format can be read by PhysX and Bullet, so that is useful for both.
The plan is to replace from PhysX simulation engine to Bullet, dropping the requirement for PhysX driver installation for the plugin. The priority for this plan will increase if there is more interest/feedback.
Thanks,
Erwin