The problem, though, is that ComiXology is basically the new Diamond. And that's probably going to be the real problem with digital comics (along with e-books of various sorts). The concept doesn't seem to work as well without a monopoly, or rather, there's no utility to competition, at least for a particular book. If you buy and download stuff, sure, that works great. But if you're only allowed to see something from a centralized source anyway...
And by the way, to look into the future of comics like this, check out what Netflix has been doing and realize that a company like ComiXology can (I don't know if they do) know which books you read, when you read them, how often you read them, and how long you spend on each page.
I agree, though, that Print on Demand has a lot of potential, and it'll have even more when someone realizes that you can open a shop half the size of a Starbucks and, with a 3D printer, a setup like the Internet Bookmobile, and a few other gadgets, you can sell from pretty much an infinite stock and little to no staff.
I can't find a good article on the topic (if I find one, I'll post it), but the upshot is that they funded their new House of Cards based on analytics. Subscribers watch a lot with Kevin Spacey, so it stars Kevin Spacey. Political thrillers average more users who watch to the end of the credits, so it's a political thriller. People who watch BBC adaptations are more likely to go on to watch more, so it's a BBC adaptation. Poof, TV crack. So what if it's the most plodding, cliché show anybody's ever seen (and oh, yes it is...), the numbers don't lie! I imagine that at least some comics will head in that direction as soon as the House of Cards numbers are in.
As to the competition in comics, themselves, I get the feeling that a lot of "culture" (for lack of a less general word) has stagnated in a lot of ways. Every action movie has the same plot, and franchises have the same arc: Origin, Victory at a Cost, Fight for Civilization. The posters are all the mysterious cloaked figure looking out over a city in ruins.
(Argh. Which painting am I thinking of, here, which all those movie posters? Anybody? Something about being over the storm? Dutch, maybe?)
Anyway, so much feels like a retread. So I wonder if it's a lack of competition of ideas so much as (like with Netflix) focusing on what's already known to sell. It'd explain the last twenty years at DC, certainly, with all the blind resurrection of every single detail from the '70s and ill-advised, perpetual crossovers without much of a plot, not to mention the absolute obsession over "core" characters, either "the trinity" or the founding JLAers.
But the thing is, independent comics shouldn't be sold like it's still 1980, in my opinion. If you have an idea and the talent, the barrier for entry is pretty darn low, and stuff never goes away. If you're not looking to quit your day job, it shouldn't be hard to find an audience over time, certainly.