Splitting a mesh at the end of a shape key-based animation I am using a series of absolute shape keys to progressively deform a mesh as shown below. Eventually, I want the soap bubble-like spheroid to detach from the originating plane and move away.

My naive approach was to create a further shape key, cut through the mesh at the last point of contact between the bubble and the original surface, and seal each of them separately.

But of course that does not work, as the split is really applied to the underlying mesh, not just to the specific shape key, so it is visible at each step, not just at the end.

How do I proceed from here?
Consider switching from 1 mesh to 2 meshes if convenient.  Render or Not Render is animatable with keyframes.  Combined Mesh is replaced with Floor Mesh and Floating Bubble Mesh.  Advantage Seams are avoided. Disadvantage Shape Continuity efforts will be needed.
Consider your mesh as always 2 separate submeshes if the Viewer cannot see seam vertices which are joined for part of the animation.  Shrinkwrap Modifier and Warp Modifier.
Consider Metaballs with reservations.  Explained Below.
Consider fluid simulations.  Larger Compute Time Demands.


Two Separate Meshes
Preliminary Results.
Warp Modifiers. Shrink Wrap Modifier.  No Shape Keys Yet.







Metaballs

Lower Portion Connected in image below.


Lower Portion Disconnected in image below.




I wrote with reservations because I have seen metaballs stop working at the most inconvenient times and simple conditions.    Then they work under other conditions such as particles.