Long overdue for a return, it would have to have Jack and Gwenn back, they are the heart of Torchwood. It would have to be set in the UK, forget the USA angle altogether, and should return to its role as protecting the earth from alien interference. We need to know what happended to the rift and the Torchwood archives, or was it all destroyed when Jack was blown up. No more running and hiding from the government, after all Torchwood was set up by Royal Charter. They should just be left alone to do their job. Bring in three new characters, we need a scientist a doctor and a "heavy" If its not going to be set in Cardiff choose a new city, somewhere where Torchwood is unknown. Underneath the Sage in Newcastle/Gateshead would make a great location. (have a look at the Sage its a fantastic futuristic looking building)Who else would I like to see back ? the obvious would be Martha and Micky but how about an alien character as well. He/She/It could play the scientist role and remain in the HQ so as to get round the problem of an alien appearing in public.
Loads of questions remain unanswered such as what happened to the Weavils, is the rift closed, was all of the hub and its numerous underground chambers completely destroyed, what about all the alien tech they had stored, in fact the opening story could be about Jack returning to the remains of the hub via a secret entrance that only he knew about and collectingf enough "stuff" so as to start up again somwhere else. There are dozens of stories still to be told about Torchwood, all we need is for RTD to want to return to that world.