Season 4 to start production in early 2017
I read on the Shetland website that someone from Vancouver Island heard today that it has been given the green light for another season. Last month another member said that she had heard it on the BBC, but I haven't been able to find any official confirmation.
For those that are interested, here is a link to the Islands official website.
They have about 12 live streaming cameras set-up around Shetland, including, the Sumburgh Airport, Victoria Pier and the Lighthouse. Some have sound where you can hear the various birds and the ocean.
http://shetland.org/60n/webcams