In ENT episode “Divergence” parts go flying off the ship during warp 5. What would happen to something at that speed without the protection of the field? Would it stay in high speed motion until interacted upon by something else (meteoroids/dust/gravitational fields)? Or would it disintegrate under this kind of speed?
I certainly don’t think they’d continue to move at a high speed. Inertia wouldn’t really apply, because the objects were never really “moving” at all. Space was moving around them, but they were stationary relative to the space inside the bubble.
So I’d say that if they survived crossing the threshold from the space inside the bubble to the space outside the bubble, they’d basically instantly become stationary.
The question is can you survive exiting the bubble like that, or would the bubble’s edge tear you apart. But I think we might actually have an answer to this, from Discovery’s last season. Didn’t Burnham survive exiting that enemy ship’s bubble in that first episode, before Discovery beamed her back aboard?