It's worth remembering particularly in recent times, neither Amazon nor B&N and to most extents Kobo are aiming to sell devices. They're like game console makers, their primary purpose is to sell books, the devices are just a way to help that. Provided they haven't so screwed up their production and ordering so as they start to lose too much, canabilising sales between their devices isn't likely a big deal. The bigger concern would be annoying people who purchased an older device or slowing sales in general. In that regard, a fixed release schedule can help since people know when a new device is coming so they're less likely to be surprised by the introduction, but that also likely reduces sales in the lead up.
Either way, I do agree all this talk of fixed release schedules or unexpected releases for Kobo is bizzarre when 2012 was the only year Kobo didn't release something in the April to June period in the past 4 years.
I'm not even convinced eInk would have told Kobo that they tried to sell the screen to B&N, it doesn't generally make much business sense, unless perhaps they're trying to convince them it's cheap because they're desperate. Kobo may have heard rumours and perhaps could come to an educated guess but that's about it.
Edit:
I should offer some clarification here. When writing the text in the spoiler tags I knew some eink ereaders used Android as the OS but they generally offer little or no extra app support not even in their own walled garden, basically they're just using Android as the OS and framework for their ereader, browser and whatever highly specialised apps offered. I wasn't aware Nook was one of those, since when the place I looked didn't mention Android. I realise now the Nook is one that uses Android and like many such devices can be rooted to allow app support. Sorry for any confusion or offense caused from my original comment. However this wasn't really what I was thinking of since while modding is cool, it's still the case that the maker didn't generally really intend it for this purpose most likely because they didn't think it would work well. Notably while some tablets do have their own walled garden without access to the Play store, they do generally have far greater app support. I do not believe this would change even if Nook had used the Aura screen, they probably would have used Android but they would still not offered much degree of extra app support. And I do stick by my point that Android is not necessarily any better for most users than some other customised OS (probably using the Linux kernel) like other ereaders use, which is why someone who is using a customised OS (as I thought Nook was but was mistaken) is not likely to switch to using Android (there is a chance if there is another reason, e.g. they want to unify the OS and app for their tablets and ereaders).
On a personal level, while I would have preferred a device with buttons, I'm mostly glad for the Aura if the alternative was a Nook device only. While it would be good to have competition or both and I may end up getting my Aura from the US anyway, ultimately B&N are way to US centric to be of any interest to me. I mean even Amazon sometimes acknowledges we exist, B&N never do so.
If you really want to talk about a Kobo oddity, consider the Mini which recently dropped drastically in price in many markets. A aggressive pricing strategy or as some speculate is it being discontinued perhaps for a Glo/front light version. If so, was the original device a mistake, or necessary/wise at the time due to market dynamics? Or is the line being completely discontinued, perhaps because the 5" market didn't work for them or they're afraid of others taking over there?