Not much to add to Forrester Research’s prediction, other than the observation that if Amazon hits the marketplace that hard, then Barnes & Noble’s Nook will probably go on the deathwatch. And if that happens, then B&N will go as well, given its current less-than-brilliant financial condition.
The upshot for indie epubbers is that time and effort spent on formats and ereaders other than Kindle (Kobo, Sony, etc.) will be even less cost-effective than before. Except as the mopping-up stage of an indie writer’s epubbing campaign, it will generally be a better use of one’s time to get another book up on Kindle than bother with other formats.