Re: when will the next generation of nokia or microsoft lumia flagship gonna come out ?
No one knows.
Gabe Aul has said on the Blogging Windows site that they'll be new devices when Windows 10 Mobile launches. But no one knows when that might be. Especially outside the US. And that's no commitment to flagship-type devices.
My guess is end 2016 Q1 for worldwide availability of any possible flagship device. If it was any sooner, they'd probably be a few leaks/rumours by now.
I think 2016 is feasible. I still hope for a worthy successor to the Nokia 808, 4.5 inches would be awesome, meanwhile camera technology keeps advancing which is good news I guess. The Lumia 1020 is kind of good I guess but the sensor is still smaller than the 808's, so here's hoping they retake the best camera route in the near future.