Would George Cole be too old to reprise his role now?
That's the only way I could see this working. Shane Ritchie -- eurgh. If anything he'd be the crap version of Tel, he's far too young to play an ageing wheeler-dealer.
An important consideration is: does the viewing public want or even care about a Minder return?
Doctor Who was clealry wanted if you judge by the pre-return media attention we used to get (espeicially in The Sun), and various other retrospective series (ala The Two Ronnies) have proved to be worth while... but Minder?
I think Minder's great but if you asked me if I wanted it back I would say no. George Cole himself said it should be left to rest as well. It ran for 15 years & had 10 series, there's no need for anymore of it, same with OFAH.
Doctor Who, as you say was different, indeed the new series is differently structured to the older series. Sci-Fi seems to be the only genre you can get away with it as you can bend the rules more than you can with the normal everyday dramas