I would not like to see the 1000 series relaunched for sure. The market that exist then is not the same as it is now. However the Xpressmusic series 5310 and 5800 I would definitely support once they have feature phone capabilities. Let 3G, internet browser and WhatsApp compatibility.
Personally I'd really, really like a 5800 relaunch.
Then again the 5800 is kinda thick. I'd recommend they relaunch the Asha 311 instead, but give it a LED for flashlight, and thinner bezels so it looks more modern.
It has to have a proper OS that can run modern apps but not Android, as that would require too much resources. Maybe the Snapdragon 205 processor.