Not quite sure whether they will or not. Like you say there was a Jackless vibe to the episodes. They've bumped off Ianto. Eve is doing some series or other (though that wouldn't necessarily stop her doing TW). RTD and whatserface are off to the US. Unless they are planning a US version I could imagine even with modern tech devoting time to running the show from there might be a hassle. But then again it had good ratings. I could see it finishing or not.