Tim Haines has just told me that he thinks ITV will be showing Series 5 in June/July, although nothing has been confirmed yet.
Also, Primeval:New World has just stared pre-production in Vancouver.
My own thoughts on this: This news does not augur well for the return of Primeval as a British series, and it looks like Series 5 may be the last, though we have Primeval: New World to look forward to. The fact that ITV are shovelling the show into the depths of summer is a good indicator that they don't really care any longer about the series, and that we've seen the last of the show after that on ITV, although the talk of the Primeval movie does raise questions as well, and interesting speculations.
I'm actually quite sad about this state of affairs, as it means that we aren't likely to see a resolution to the plot introduced by the cliffhanger at the end of Series 5, and with several of the cast already doing other projects, this just doesn't augur well for the future of the series on ITV.
That said, as one of the show's co-creators has said in the past, Primeval keeps coming back from extinction, so one never knows. And there is now the hope as we wait and see what Primeval: New World will bring us.