Probably, but only in the same way that the Alliance rules the Verse in Firefly. There will always be Independent browncoats and fringe planets. Currently these confederates are as motley as you would expect: Barnes and Noble, Apple, Google and Kobo being the rowdiest.
Barnes and Noble knows how to sell books. They are and have been primarily a bookstore. Having survived the economic downturn and the rise of the e-book, they have advantages over Amazon when it comes to relationships with libraries and book distributors. Plus they have brick and mortar stores, which I hear some people still go to. B&N also makes a mean eReading device, that along with Kobo and Sony will read .epub format (the universal format that Amazon is doing its best to bury like they did to .mobi a while back). The Nook, by most measures, is as good or better than the Kindle. (Their actual eReader software is better, so thhppp!)
While I expect a few good things to happen via apocalypse (ie. a flourishing of “buy local first” and “slow foods” campaigns), I also suspect lots of crappy things could happen as result of global, wholesale Armageddon. In the comments below I’ll want to hear your list for the top three things that will suck the most, but to get the old zombie fodder cranked up, I’ll share mine.
As a writer I’m on-line more than I’m asleep. Heck, sometimes I use the internet while I’m asleep. My internet time is like dust particles in the air I breath. Without it there wouldn’t be any creative mucous buildup, and therefore nothing spectacular to blow out on the page.