Henshall bid farewell to the murder mystery TV favourite after series seven aired earlier this year, following almost a decade spent portraying its protagonist, Detective Inspector Jimmy Perez.
He appeared on Sunday with Laura Kuenssberg and discussed the future of the show and whether it can continue to work without Det Insp Perez’s character.
Henshall debuted the role of DI Jimmy Perez on BBC One in 2013 in the first TV adaptation of the award-winning novels by crime writer Ann Cleeves.
After nine years in the role, he made the decision to quit at the end of its seventh series to explore other acting opportunities.
The crime drama will return for an eighth series next year, with a new lead and further casting to be announced in due course, the BBC confirmed.
Asked why he left, he said: “To be honest, I thought we’d murdered enough people on a small island.
“I think 10 years is a very big chunk of time.
“I think we’d explored his personal story.
“I think all the ends of those threads were needing to be tied up in some way.”
He added: “It means that there’s a lot more work for Scottish actors, for a crew, there’s more money coming into the islands.
“You know, so, I just hope they don’t make a mess of it, that’s all.
“I think it’s certainly the right thing for me to go.
“And I wasn’t going to leave.
“(Shetland writer) David Kane and I, after series five, sat down and thought how many more of these can we credibly do?
“We thought that if we’d another two seasons, then we could tie it up and end it well.
“But that was to end the whole show, it wasn’t just to end Jimmy Perez and for him to walk away.
“That was the show that was going to end.
“The BBC have decided that they want to resurrect it and reinvent it to a degree, so it’s not going to be the show that I was in, but it does give them room to do something different.”