Well this is interesting. For some time I felt that Nokia were going crazy by having too many different models but it has kinda worked out. I kind of see an opportunity to make it clear what models are for what.
So this is what I think each should mean:
High End / Flagship
1500=Phablet
1000=Camera focused
900=Mid sized
800=Compact
Value
1300=Phablet
700=Camera Focused
600=Mid sized
500=Compact
So for the 830 I would say it must have flagship Specs in a compact form factor also it should inherit removable battery and cover along with SD card slot. I believe we will considering the 630 and the 1520 has.
So Specs
Processors: Snapdragon 800 chipset
RAM: 2GB
Memory: 16GB Internalwith microSD, up to 128GB
Display: under 5 inch screen with more than 350 PPI and Gorilla Glass
Wireless:Wi-Fi 802.11 a/b/g/n/ac, Bluetooth v4.0 with A2DP, NFC
Camera: at least 8MP zeiss lens maybe BSI
-Video 1080p@30fps with HDR microphones
-Front at least 720p@30fps
Battery: at least 2200 mAh removable battery
Sensors:accelerometer, gyro, proximity, compass
Colours: at least five colours of back cover
LoudspeakerVoice 73dB / Noise 66dB / Ring 74dB
Audio qualityNoise -89.3dB / Crosstalk -89.4dB