Sure, but I'd expect that Apple would provide some API for you to designate certain tasks as intended to be run in the "Deep Background". With the understanding

Sure, but I'd expect that Apple would provide some API for you to designate certain tasks as intended to be run in the "Deep Background". With the understanding that such tasks are on a very short leash power and capability-wise, and may be arbitrarily cancelled—like iOS's forcible app killing, but at a smaller grain. (Does GCD have a facility for the dispatcher to unilaterally do this already?)