Probably meaningless to the USA market. Afterall, even if Engadget is on target, and that is a big if, all 4 of the listed companies have a combined market share of what? Perhaps 5-10% of the USA market at best?

Plus, listening to anything Engadget says is like getting your news from a grocery store tabloid.

Also, I saw nothing in that brief statement about new ebook readers. It appears to refer to their book stores. Sony might stop producing ereaders while maintaining a book store. As a matter of fact, I think USA law would force them to support the ereaders for a certain time period after discontinuing them.