doctorbadwolf
Heretic of The Seventh Circle
I never like to ignore any facts, but everything I recall having seen contradicts that idea. By the end of 4e we were completely out of D&D and the local stores stopped carrying the books entirely. The playtest made some minor waves in the local stores (not for us), but when 5e was released everything changed. Not only are the local game stores carrying the books in prime locations and making money on them, but so are regular book stores.
As to new players, I have seen TONS of completely new-to-ttrpg players come into the game in the last couple years. There are obviously many reasons including new media like Tabletop's Titangrave, Fiasco, and other RPGs but even relatively savvy (for new to the hobby people) are choosing D&D, even if it wasn't what they were first exposed to. On several occasions I have heard from people working with or at Wotc say that demographics have shifted much younger but I have yet to see anything resembling data.
4e had a ton of players, so far as I can tell, compared to anything other than right now, or the "golden years".
Encounters was a big thing, also.
And the whole "nerds are cool" thing has more to do with the rise of DnD than any Edition, imo. That took off during 4e, and has continued, but has rarely had any remote mention of newer DnD products.
Also, not to beat a dead horse, but the DDI sub numbers before the playtest was announced were pretty big, which is a good indicator.