Join Date: Nov 2010
Location: Alexandria, VA, US | Age: 27
The plan goes something like this, at least as far as the US is concerned:
Stations are given the opportunity to participate in a reverse auction to possibly be bought out by the government, if needed, to clear the top end of the UHF band for spectrum. How much spectrum is bought depends both on how many stations choose to participate in said reverse auction as well as whether the revenue from the forward auction fully covers expenses of the reverse auction. As such, whether it's 38-51 or 30-51 or 44-51 (or some other group of channels starting at 51) is not yet known.
You are correct, no station can be forced to VHF, but stations can seek money in the reverse auction in exchange for moving to VHF. Similarly, stations can seek money to go off the air on one channel and channel share with another station (glorified subchannels).
Non-participating or unpurchased stations may still be required to move, particularly but not exclusively if they are in the "cleared" part of the UHF band, and those moves will be compensated by the $1.75 billion fund Congress established. Whether or not that's enough money is up for debate, but since Congress set the number, Congress, not the FCC, is the body that would have to adjust it.
Comments are my own and not that of my employer (the FCC) or anyone else.