i reckon that, if the 650b thing gains any more traction, most major bike makers will add a cursory 650b effort to their quiver, just so they won't seem out of touch, behind the times, etc...
But, most of these "efforts" will be semi-pointless exercises, like the beasley twins. The idea behind the 650b size was to offer bigger wheels with bigger travel without effing up geometry. So, the geniuses at haro started out with a few full-rigid things. Whatever; they've got a full-sus one in the works. might even be available already.
Thing is, right now, there's a small handfull of tires and rims available for 650b. This is what we saw initially with 29ers, and was the main reason i waited to build a 29er. However, the industry has already proven more willing to make moves with 650b options, so it ain't that big a deal. But me, i'm waiting. Or, more likely, i just won't bother.
ps-you can cram 650b's into many frames with big clearance, like surly 1x1/instigator, on-one 456, etc. Soma makes a thing they call "B-side". Carver makes a Ti killerB. Do a search; there's already plenty