Considering disks as chunks and mapping zvol structure over chunks so you can use asymmetric size disks. But what ensures zraid block coverage on more than one spindle? This probably is safe for a large enough set of drives, but what is the threshold?
If you mean upstreamed to OpenZFS, then yes. The blog links to a openZFS leadership meeting so I would assume they are all in agreement that this will be in the mainline codebase.
Readit News
Is it going to be accepted upstream?