SONY has announced that it is going to close its Reader store in U. S. and Canada. on March 20, 2014. The customers and their libraries will be transferred to Kobo so long as the titles are available on Kobo Store. If a particular title is not available on Kobo, SONY has advised the readers to back up the files. They will release an update for Sony Reader software so that further purchases on the devices can also be made from Kobo.
More details are available on this FAQ page.
Despite being one of the early players in e-book device markets, SONY clearly has not been able to sustain it. Thankfully the transition to Kobo ensures that they aren’t leaving their customers unsupported.