I don't really get this "feature". You could always put one app in an appstack and if I really wanted call it a package. This isn't exactly anything new. The only problem is if you had 20 appstacks (packages) it would take forever to login, which of course in app volumes 4.0 it takes forever to login with 20 packages applied anyway, so...
The other issue is there is a limit to the disks you can have per storage controller on the VMs themselves:
The maximum number of disks depends by the controller type:
SCSI is the default and most don't change it so you can go to 60 virtual disks. That is 59 packages that you can have max from what I can tell unless I'm reading this wrong and you would have to have 4 storage controllers to do it.