From what I've read, the 5GHz radio module (when it's released) will require more power than Cisco's current inline power implementation can provide. This is apparently due to the current 5GHz chipset power requirements.
If a lower power chipset is produced in the future, it might be possible to use the current inline power implementation.
There's also some question as to what will happen when inline power becomes a standard, and how Cisco will support migration from their current implementation to the standard.
