Worse, it's unlikely that these white spaces will be useful for devices such as phones. The reason is that the frequencies available in the white spaces vary by locality, and they cover a wide range of frequencies in the UHF television band. Those frequencies range from 470MHz through 700MHz. Frequencies above that have already been—or are about to be—auctioned off for mobile carrier use.
If you've been around long enough to remember the old days of UHF television, you'll recall that getting a good signal at any distance was problematic. For a television signal to get to you, the broadcaster had to transmit using power in the tens to hundreds of thousands of watts of what's called effective radiated power. While it's certainly possible to send out data at those power levels, remember that data communications is a two-way process. And your phone typically puts out less than one watt of power, usually a lot less.
What this means is that you might be able to receive data, but unless you're next to the transmitter, it'll never be a two-way conversation. One way to overcome this is to place thousands of hotspots in a community as some cities do with municipal WiFi. This works, although with WiFi it really only works well if you're not inside a building. With the proposed UHF solution, it will work inside buildings, but only to a certain extent.
As you'll also remember from the days of UHF television, signals didn't go over hills, around trees or through thick concrete walls. This was one of the biggest problems suffered by UHF broadcasters. The only thing that really kept them alive was cable television. UHF data communications won't work any better, but if thousands of local hotspots are available, that won't matter.
Another major problem is this isn't a nationwide solution. Each locality has different channel allocations. So the white space may be at different frequencies in different areas. Because of the range of frequencies, it'll be difficult to build the necessary radios and antenna systems so they'll fit into mobile devices.
So what will happen? The white space solution is a natural for fixed wireless data carriers where you don't need to worry about more than one frequency. This is something that can be accomplished easily and fairly inexpensively. But will it be free? That’s another question entirely. One way or another, those local data hotspots have to be paid for, and it's not coming out of the FCC's pocket. That means it's either your taxes, or you'll pay for it directly. But no matter how you look at it, there's no such thing as free when it comes to data transmissions.