Yeah, okay, so there's kind of a bubble. The 1849 feel the ebook market has taken on isn't necessarily a bad thing, but naturally there are big changes ahead.
There are two or three major issues at play, here. The first is that the low barrier to entry has flooded the ebook market with substandard books.
The second is the free book market, which is already a serious force to be reckoned with.
The third issue is probably the notion of an upcoming 'bubble' event.
In the long run, these details will only enhance the careers of quality writers. It will take more work at marketing to stand out from the oceans of dreck out there, but good writing will take over at that point.
As writers, we're going to have to accept that there are distinct classes of ebook readers. Some download free ebooks exclusively. Some buy everything they read. Some people exist between these two extremes. The important thing is to recognize the difference, and incorporate both into your marketing strategy.
Don't put too much energy pitching to people who aren't going to buy it anyway, but throw them a bone. A free book or two can go a long way by word of mouth. A good author can actually, by nature of their personality, convince someone to lay down cash when they could get the same text for free elsewhere. Be that author.
Site like Goodreads and Shelfari will be the filter that the ebook industry needs to separate the good, bad, and the ugly. Crowd-sourced reviews will make or break some ebooks in the upcoming years. Again, stay on the side of good writing.
I posit that there will be no bubble, as not too many people are really making a killing at self-publishing at the moment, anyway. Give it a few years to grow into a monster, then, bubble, sure.
But what we'll see first is more of a sifting and culling process. And presumably a slow down in the flood of new titles hitting the shelves. Who has time to read all this stuff?