Honestly, DC's problem is that they're too afraid to take risks I feel. Ok, New 52 was a pretty big risk, and it paid off in the short term, but things just slowly went back to the way they were. Also, New 52 had this problem of being overwhelming in terms of releases. They released everything at once, its hard to figure out what you want. Contrast to Marvel Now! which was released over a span of several months, so there were only a few #1s per week, easier to keep track of all the new stuff. Marvel Now! granted wasn't as big as New 52, though it wasn't anywhere near as ballsy, and Marvel Now! was clearly just made as a marketting ploy to counter act New 52.
Really, though, when it comes down to it, Marvel is not afraid to try and push oddball names in hopes to make them bigger. Guardians of the Galaxy is their current test subject in that regard, for lack of a better word, and Iron Man is probably their most successful using this business strategy (and it sure as hell paid off.) Whenever I see DC coming out with something new, it's often More Batman, More Superman, or something involving both (like the JLA.) Heck, I remember like 2 months ago or something, they cancelled 4 books, and replaced them with...2 Superman books, a Batman book, and a 4th thing that was actually something newish?
It's not just comics; their movies, animated stuff, and even games heavily rely on those two. I know they're DC's biggest faces by far, but it wouldn't hurt to try and push some of the other JLA heroes into the limelight. Easing up on Batman a bit and putting some efforts into promoting another character probably wouldn't hurt too much. Batman's popularity isn't going to start waning anytime soon, so you really don't need to push him anymore, just acknowledge him when something new of his comes out and people will buy it because "It's Batman." Put more of that Batman marketting efforts into someone else who needs it.
But yeah, they're marketing to a specific fanbase only, and not trying to bring in new readers. New 52 was the only time it felt like a strong push, and once the hype of that died out, they basically just said "fuck it, back to business as usual."
That said, wasn't Dididio also the guy who whined about 52 being the worst thing ever, then said "Countdown is 52 done right!"? Everytime I hear about stuff related to Dididio, it never sounds good, but maybe I've only heard of the bad stuff.
