This is not a shock, Sony lost interest in ereaders and Reader Store was next. But I am annoyed, I have to be honest. 
I have a perfectly awesome PRST1, I love it, and whenever I've had any issues, the Sony support was very good and quickly resolved whatever was needed. 
 
My son has a KOBO, I must be honest, KOBO hasn't provided much in the way of good customer service... we find KOBO frustrating at times.  There is a good selection of ebooks, their prices are right, that is not the issue - the issue is support/customer service.  
So, anyone who owns a Sony ereader is pretty much on their own, they won't get much support after March 2014 from anyone...  I hope KOBO are about to hire a whole bunch of new customer service/ support reps and train them in the transition - and that the transitions are simple and workable.