It's interesting to read everyone's expressed opinion, so I'll offer mine (with the caveat that - as my drill sergeant expressed it - "opinions are like as*h***s: Everyone has one."):
I don't think Sony is exiting the ebook business; rather, I think they're preparing for a new line of Readers.
I was in Tulsa yesterday, at Borders, and they had on display both the 505 and 700. I asked him if he had any 700s for sale and he checked. There were none. He then called Sony to see if they could sell me the 700 display model and they told him (from what he told me), that he was to take the entire display unit down. (If there was more information given, the manager did not share that with me.)
He then called the other Borders in the Tulsa area and they, too, had no 700s for sale.
Don
P.S.: Remember, I'm giving you my opinions and sharing the information that was given to me. My opinion about all this is probably as valid as "yours." Pardon me, now, while I go to the bathroom....