Rob, there is currently only one flash cartridge in the country. This will change as more become available. This is the method by which Subaru is currently processing the claims. I have no other information to give you, unfortunately. The shipping delay is a temporary problem that will go away as soon as more flash cartridges become available. 4-6 days is a decent estimate. I hope to give my customers a 3 day turnaround, but obviously chaos is the rule rather than the exception when you are talking about shipping anything in this day and age. Appointments will have to be spaced out somewhat, obviously SOA can't flash 200 ECM modules simultaneously. You'll have to be very patient.
As far as a rental vehicle, you will have to check with your local dealer on that issue. Different dealers have different policies and they will have to work with Subaru on that. Obviously I have no information about your local dealer, you will have to query them on that.
As for the changes being made, speculation solves nothing and only serves to muddy the waters with misinformation. We will have to wait and see.