D&D is the only mainstream brand the industry has of its own, and WotC is in a position to leverage that to grow the industry in ways that other companies can't. So a successful D&D means a bigger RPG industry with more players in it.
Very true, but there's nothing new that makes 5e any more of a draw (other than a new box on the shelf, that is - that's something).
The Encounters program is about it as far as trying to /attract/ new players go. And, casual play is a great way to introduce new players. I've seen it first hand, it's only one data-point, but the FLGS where I've alternately run and played encounters has 30 or so regulars, only half a dozen of whom had played D&D before showing up for Encounters. Three of the 5 current DMs started with Encounters, two of them were running games within less than a year of first playing it. And, that doesn't count the folks who started with Encounters, formed into groups and moved on to home campaigns (don't know how long those lasted, but there were several of them).
That sounds all rosy, but, at the same time, the edition-war rift in the existing community meant there were a lot of established players who were only buying from one segment of the industry, and the new players, in turn, weren't much drawn to that segment. So Encounters might have added more gamers without adding much in overall industry sales. Conversely, when d20 made a big splash by going Open-Source, lots of new (and old) companies produced lots of new nominally-compatible games and supplements that were complementary to D&D, so any new players added were potential customers of a lot more product, and, perhaps more importantly, longtime D&D-only players were finally given a path to other products, as well. So it might have been that the OGL helped grow industry sales without necessarily adding a corresponding number of new players. (For that matter, it's hard to blame D&D for not attracting new players in the 90s, when CCGs and LARPs drew off a lot of potential TTRPGers).
So, 5e still has Encounters, and with product on the shelf, there's something to buy. That's good. Really, it's fantastic - that Encounters kept retaining players and staying active in stores even with no new product for those stores for two years bordered on a miracle. The prospect of something new should really kick things up into high gear.
The snag I see is that Encounters looks poised to become less casual play and more Living Campaign style. No more, 'oh your character died, erase 4 surges and we'll see you next week.' Certificates to prove you have magic items. That kinda thing. We'll see how it shakes out, but that may make it a little harder for the program to attract (and more importantly retain) new-to-the-hobby players. OTOH, it might well attract/retain /returning/ players - that vast pool of guys now in their peak earning years who tried, or at least bought (or found under the Christmas tree one year), D&D as kids in the fad years and haven't been seen since.
That is, if there's some peep in the mainstream to remind them of it... for years, a few voices have been saying that WotC should finally do some mainstream advertising, maybe it's time?