The various posts on their twitter feed seem to suggest it's temporary.
https://twitter.com/KoboHelp/status/332145240855154688
https://twitter.com/KoboHelp/status/332157644011876354
https://twitter.com/KoboHelp/status/332528189203177474
https://twitter.com/KoboHelp/status/334397906696163328
https://twitter.com/KoboHelp/status/334456782405644288
https://twitter.com/KoboHelp/status/334760222428123138
https://twitter.com/KoboHelp/status/334792674907410432
https://twitter.com/KoboHelp/status/335419063910166528
https://twitter.com/KoboHelp/status/335492451856969728
As you can see, they even suggested it would be back on the 10th once. I don't know if this was a mistake or they really were expecting it to be back but it was more difficult then they expected (either way they should have stuck with the 'we don't have an ETA' line in retrospect). Considering the number of twitter posts they've had about it, I doubt they know know it's in a fair amount of demand although I guess there's no harm emailing them just to reaffirm the point.