Having just visited a Barnes & Noble at the beginning of the week (in search of a MM and DMG), I can honestly say, their organization of these materials was little better.
For 5 minutes I was scanning the hodge podge shelves, with rows of Pathfinder materials, 2e reprints, 3.x PHBs, MMs and DMGs, 4e PHBs (1, 2, and was there a 3?), MMs (1, 2, and was there a 3?), and DMGs (1 & 2?)...eventually, in disgust, I happened, quite by accident, to notice the remnants of the 5e "end cap" it's called? Which was about 15 PHBs and a half dozen Rise of Tiamats, stacked , face up, on the floor...and a single MM remaining on the facing out shelf (which I scooped up after checking a few pages for printing smears and the like, all good. It was MINE!).
Has the DMG not hit B&N yet or were they just all gone from the holiday rush? I am chalking some of the disarray of the whole thing to the fact it was 5 days after Xmas and the store was still reeling/trying to get rid of its holiday stock. But the fact there were NO 5e books on the "normal" PF/D&D/gaming shelf where I would imagine everyone would go to look, was a bit disconcerting. But the PF materials do, notably, overrun the shelving compared to 3 past editions of D&D.
When I got my PHB from them [a different location, but a B&N], in Sept, I also could find noting but past editions on the shelves. But then, after asking, was directed to where the PHB and RoT (that's the one with the white dragon on the cover, right?) were right up front, on the "new release/hot stuff" tables in the front of the store.
I was surprised the (new enough, I would think) MM wasn't to be found their as well.