Failure to launch
Based on the statements that emanated from the 2008 attempt to reboot the series, the simplest answer is that despite a strong and consistently vocal fanbase, the reality is that the rights holders (B7 Productions) have spent decades struggling to secure funding for the show to be rebooted.
B7 Productions, which is also involved in the acclaimed series of
audio books related to Blake’s 7, released its own statement in
response to the news, in which it stated that it would seek another
partner for development. “Sky deciding to not proceed with the planned
TV revival of Blake’s 7 is obviously disappointing, but the
development process has resulted in the dynamic reinvention of this
‘branded’ series,” the company said. “As Sky were the minority
broadcaster, there is a huge opportunity for investment in a TV series
that is fully developed, has genuine global appeal and has exciting
360 degree exploitation opportunities. With much praised scripts from
lead writers Richard Kurti and Bev Doyle (Going Postal) and 60 per
cent of the finance already in place, by anyone’s standard we have
pulled together a compelling package. We are confident that this
reboot of Blake’s 7 has the creative and commercial credentials that
will enable us to find a partner with the vision to recognise the
strength and enduring appeal of the show and the opportunity it
represents to produce a bold new drama series with significant
BLAKE’S 7 REBOOT CANCELLED
So what's going wrong?
The show certainly has a cult following, but unlike BSG, Westworld or MacGyver it hasn't been repeated enough to have a consistent place in the public memory. It's not been shown again on UK TV since the 1980s and there was extremely limited interest in the audio reboots on BBC Radio 7. With regard to US TV, the original show has too few episodes to enter syndication, further limiting its potential to gain a global fanbase.
As far as unsubstantiated rumours are concerned, I've read internet chatter that suggests that various networks have expressed serious concerns about B7 Production's expectations regarding how much money needs to be spent on the show and how many episodes need to be commissioned in advance in order to do justice to the show.
“This will be a big show and that’s why it’s taken much longer to make
sure we get it right… Sky want to get it right,”