The stars are slowly aligning for a 6" 1080p Nokia phablet with Snapdragon 800 power. The information is pretty circumstantial, but it's there – in a Bluetooth SIG filing and from data collected by AdDuplex.
AdDuplex collects stats on Windows Phone handsets and found in its logs a few unofficial Nokia devices like the RM-937, RM-927 and RM-940. RM-937 reported a scale factor (a measurement showing the relation between screen resolution and size) of 150, which is what 720p phones report. However, Nokia doesn’t have 720p devices, only WXGA (1280 x 768 instead of 1280 x 720).
So, either Nokia is making a device called RM-937 with a 720p screen, or this is a 1080p device with a larger screen diagonal. Again, it's pretty circumstantial. The RM-940 was apparently the same device running on AT&T's netwok and the RM-927 was on Verizon.
It was the RM-940 that showed up in a filing with the Bluetooth SIG. What's interesting is that the filing is linked to another one made by Qualcomm that lists a number of Snapdragon chipsets: MSM8974; MSM8x26; MSM8926; MSM8x10; MSM8916; MSM8x12; APQ8074.
The first one (ending in 74) is a Snapdragon 800 chipset (quad-core Krait 400 CPU, Adreno 330 GPU), then there's the xx26, which is a Snapdragon 400 chipset (quad-core Cortex-A7, Adreno 305) and finally the xx10 and xx12 chipsets, or Snapdragon 200 (dual-core and quad-core Cortex-A7 respectively, Adreno 302). It's not clear what the xx16 is, but it's probably Snapdragon 200 too.
Nokia already uses Snapdragon 400 chipsets for its lower-end Lumias but not ones with Cortex-A7. And it hasn't used Snapdragon 200 chipsets either. So, even if the Snapdragon 800 rumor doesn’t pan out, the RM-940 will at least use a quad-core Cortex-A7 (it's unlikely that a 720p device, let alone a 1080p device, will use Adreno 302), which is news too – Microsoft has yet to flip the switch on the quad-core support for Windows Phone 8.