Kobo informed me this evening that they have retired the Kobo Aura One ereader, and have replaced it with the Kobo Forma.
Thanks for your note. Kobo Forma is taking the place of Kobo Aura One as our premium device.
The Aura one is out of stock on Kobo.com, and Kobo's retail partners in Canada, EU, and United States are no longer carrying it (TBH, I am not sure anyone actually carried it in the USA).
Launched in August 2016, the Aura One was an largely unremarkable ereader with a 7.8" Carta E-ink screen. It retailed for $230, making it a decent value compared to the first Kindle Oasis, which launched in spring 2016.
The Aura One's biggest claim to fame was the size of its screen (the largest Kobo ever shipped) and Overdrive integration. It was the first ereader to ship with this feature since Sony retired its ereader line, but the Aura One is not the only OD-equipped ereader any more. Kobo released a general update several months ago that added Overdrive integration to all current Kobo models.
P.S. The reason I am down on the Aura One is that I prefer another model. I think the Aura H2O was the better ereader because it had a much nicer shell. Alas, Kobo decided to go for bland shells after that.