That is weird. Like what if this was a hit and run, USAA won't do anything because the other person didn't talk to their insurance company?
What should happen is that USAA takes care of everything for you, minus your deductible (and rental costs, if you don't have rental coverage), and IF they get in touch with the other insurance company and resolve it - they send you a check back to cover it.
This has always been what happened with my multiple (ugh) accidents. Farmer's comes out, checks my car, asks for the deductible, I get everything fixed, and 6 months (or more, since they're slow) later I get a check in the mail because they found the other driver at fault. I had ONE instance of them not being able to contact the other driver/insurance... in that case, I was out the deductible, but they still fixed my car and did everything else. It's kind of blowing my mind that USAA isn't doing that - isn't this the bare minimum that an insurance company needs to do?