I'm thinking that Mearls can only really say this now that the DDM have been canceled. It may even be that this is the first sign that WotC is (hopefully!) moving back to a "minis optional" approach. If they aren't going to produce their own minis, they almost have to.
I was thinking much the same. Not
quite the same, because Mike Mearls has always been up front about his enjoyment of old-school play; if his public announcements were driven by WotC's design and marketing priorities, he certainly would have kept his mouth shut about running a monthly AD&D game! So I don't think he's suddenly had some kind of gag order taken off.
I do, however, agree that this may indicate the start of a move away from miniatures-dependence. That dependence was a feature as long as DDM was a big money-maker for WotC. Now that DDM has been canceled, the feature has become a bug, adding another barrier to entry to a game that has too many already. I think that unless that poll shows a
very strong preference for minis, we will see a trend away from the battlemat in official D&D products over the next few years. Eliminating minis-dependence from 4E is a pretty tall order, but they'll do what they can to reduce it, and when the time comes for 5E they
will eliminate it.
It's funny. I have a ridiculous miniatures collection--close to 2,000 at last count. (It got to the point where I made a spreadsheet just to keep track of them all.) I've dabbled in metal miniature painting and modding, and had a lot of fun with it. I love my minis. And yet, I'd be happy to see them become optional, even deprecated. In my experience, when the battlemat comes out, the game slows to a crawl and immersion is replaced with number-crunching and square-counting.