The more users that demand high-bandwidth access, the more avenues the
industry must exploit to meet demand.
I suppose the MW/HF spectrum could be "given over" to BPL,
supplementing DSL and cable to deliver broadband for non-mobile users. 30
mHz is plenty, especially with compression methods constantly improving.
BPL doesn't need to supply all of a community's broadband needs, it's just
part of a larger system.
As with carrier-current AM, you don't need an antenna. Inject the rf
at the breaker panel of any building, and service that whole building with
broadband via the power outlets. Interference from natural sources is not
an issue, because the signal is not "broadcasted". Would it wipe out the
ability to use an AM/SW radio in that building? Of course. But a listener
no longer needs an analog AM radio to listen to radio programming.
I suppose VHF-UHF can deliver local broadcasting digitally for both
fixed and mobile reception. Higher frequencies can deliver cell, digital
2-way, broadcast (such as XM) and broadband wireless data via cell sites
and satellite.

The farthest any terrestrial antenna would ever need to radiate is a couple
of miles!

Electrical costs or otherwise, broadcasters would be thrilled to retire
their transmitter sites. Good-bye insurance, tower maintenence, replacement
tubes, land leases, ground radials, lightning strikes, vandals, generators,
rodents, bullet holes, cell tower de-tuning, and old-fart RF consulting
engineers making $300 an hour. Just ask Clear Channel.

Pete
KQ5I