The New Zealand-born back-row, who has 16 national team caps, returned to training in January after a three-month ban handed out by Scottish Rugby for “gross misconduct” over alleged cocaine use. Since then he has been playing for Edinburgh in the Guinness Pro14 and trained with Scotland last week, but his future lies away from the capital.
The 29-year-old arrived in a blaze of publicity in 2015 when he made his debut against Italy in a World Cup warm-up match. He was eligible to play for Scotland through a grandmother from Fife and was part of the Highlanders squad that had won the Super Rugby title earlier that year.
Four caps came at the World Cup in England and he then joined Edinburgh, with Alan Solomons in charge, on a two-year deal.
Last summer he penned a new one-year contract before his off-field issues and, with his exit at the end of May now confirmed, it will be interesting to see where he ends up.
Cockerill said: “John won’t be staying.
“He is the same as a lot of other guys, we have a lot of young guys coming through and financially we need to spread our costs.
“We have to make sure we are getting value out of our budget. We have guys like Jamie Ritchie and Luke Crosbie coming through who can both play at seven, while Hamish [Watson] is first choice for Scotland.
“Add in John Barclay [who arrives this summer] and there is a lot of good back-row players. We need to get value from the squad and get the right balance moving forward.”
Cockerill, whose side face a crucial league match against Munster at BT Murrayfield on Friday, has admitted he still has further new signings for 2018/19 to announce with the front row his priority.
He said: “We’re still looking at a couple of props potentially to bring in because we need to strengthen that area when guys are getting taken away with the national side.
“Next year the international periods [the Autumn Test and Six Nations] are going to be more and more important. If we’re going to compete we’ve got to be competitive in those spells and win games.
“We’ve done all right this season so far in the international windows, but the better this team gets I’d expect more people to be taken away for the national team, so it’s trying to get a balance there as well because if there’s injuries it really affects you.”
For the rearranged game later this week, the likes of Mark Bennett, Ben Toolis, Cornell du Preez, Hardie and Magnus Bradbury are back from Scotland camp and the head coach added: “They are very important players to us and we will put out a good side on Friday to compete.”