P Kev's new shtick is a little transparent.
I think the White Walkers are more interesting because they're not just some unthinking force crashing southward, but an actual army with organization/tactics. But they don't really need any supply lines or can be bogged down by the weather like a conventional army, and they can replenish as they go. I guess the 64k question is how they breach the wall, but after that, how many soldiers are they going to net (people killed/zombies created - zombies killed) at/between the Wall and the South? Yikes.
The geographical location of Hardhome would lead one to believe that the WW's came for it specifically, as it's somewhat out of the way on the path to the wall.
Unless they're just tracking down the coast.
http://quartermaester.info/