Riccardo Palombo of HDBlog.it reports that his sources are saying that Kobo will be announcing two new ereaders this spring, possibly before Easter (5 April). He reports that both the Pika and Alyssum are coming.
Update: I have confirmation from a second source.
The Pika is said to have a screen resolution of 800 x 600, a touchscreen but no frontlight, and basically be an updated version of the Kobo Touch (which not so coincidentally is out of stock at Kobo's website).
The Alyssum is described as a $149 Kindle Voyage competitor with matching screen resolution (6", 1072 x 1448) and quality. It should have a frontlight and touchscreen, but I don't have any other solid details.
If that price is correct then the Alyssum is going to cost just $20 more than the 2 year old Kobo Aura, and $30 less than the Aura H2O. Curiously, the latter device is out of stock right now, but I wouldn't read too much into that detail. No one is expecting that device to go away, not when Kobo has little competition for the 6.8" screen.
All in all, these rumors are nifty, and they fit with the technical details which had already leaked. But at this time there is still no FCC filings or other concrete leaks to prove the existence of the upcoming rumors, so I am taking them with a grain of salt.