As a fan of the original BBC series from the late 1970s I'm glad to see that Sky has given up its plan to reimagine Blake's 7, though it seems like there is potential for it to be picked up by another producer. I'd not be keen on a remake of the original with the lead characters like Blake, Vila or Avon recast given how definitive Paul Darrow was as Avon.
A series set after the original could be viable, e.g. "Blake Lives!" with new rebels against the Federation inspired by the memory of Blake and maybe led by survivors from the shootout at the end of the fourth series. Potentially if the setting is not too long after the events of the series the Federation could still be led by Servalan, but it might be better to make it a longer gap and create a clear break in the way the Time War was used in Doctor Who by Russell Davies.