Whoa! Totally unexpected! I'm taking the optimistic view that this will strengthen Kobo in the U.S. and internationally (they have a head start on B&N). Even though I opted out of the Vox, I do want Kobo to succeed, because better competition and more choices in the market is generally better for consumers. (If only we could get rid of agency pricing ...)
It feels a little weird that they were bought by an e-commerce company, but it kind of makes sense, too. I think one of Kobo's weaknesses has been its marketing reach and strategy, though they seem to have latched onto a more "open" philosophy compared to Amazon and B&N. As long as Ratuken allows Kobo to fulfill its vision, I think this is a good thing. If it starts to cloud the vision, then we lose out, I believe.
But I'm not an expert in this stuff.