As more information pops up on this topic, it's possible this whole debate is pointless, but still strange news. It seems some sites have been able to somewhat confirm there will be no desktop CPUs at all in Broadwell. If that's true, of course BGA makes perfect sense as the chips would be used for all-in-one's at the "high" end, and go down from there to laptops, ultrabooks, etc. But no desktop CPUs? Hmmmm...
So, who knows? Of course Intel itself will neither confirm nor deny anything at all about products that are not yet made public (by Intel).