Perhaps, much like how your smartphone waits for a WiFi connection before downloading or uploading large amounts of data, the plane could scale up how much data it sends: It could transmit basic flight data at all times via VHF, and then a full stream of data from the FDR when theres a communications satellite overhead. Ultimately, even though FDRs might record more than 100 variables and diagnostics, were still only talking about a maximum bandwidth requirement of a few megabits; realistically, a few hundred kilobits per second would probably be more than enough.
With the Air France AF477 FDR never recovered, and now the very high profile disaster of MH370, I wouldnt be surprised if the airline industry finally takes a serious look at mid-flight aircraft monitoring.