I know that ITV have been making some drastic cuts recently so maybe that's why they've not re-comissioned Primeval? If that is the case, then maybe Channel 4 or BBC 1/2 could buy the rights (or whatever it is that's involved) to get it back onto our screens. That way ITV could make some money from the sale and we'd benefit by a new Series being made (even if it does end up on a new channel (so long as it's not Channel 5, lol))
Quite clearly there is scope for at least one more series, what with the idea that Sarah said she'd had, with Abby and Connor stuck in one time period and Danny stuck in another. I think it would be very unwise for any Channel to have left things so open ended in this way.
You can see by the way the series panned out and by the finale that Tim Haines and Adrian Hodges were reasonably confident that there would be a new Series when they'd written this Series.
So let's get Series 4 comissioned a.s.a.p. people.