Ok it's great that the chromecast will be able to do this but saying no impact on classrooms is not true. Have you ever actually looked at how much spectrum utilization goes up when doing a cast? This can be problematic in already crowded dense classroom.

The upcoming apple method which will setup via an adhoc wifi between the device and Apple TV will be even worse for a WLAN. You also have to watch how much soectrum display mirroring uses as well. But how can you think that the 2 devices doing airdrop would be ok for your WLAN. This will cause interference and collisions for enterprise wifi because they could be tx and the same time and thus cca will kick in. Causing backoffs and retransmissions.