NORTH Melbourne is yet to open contract talks with free agents Scott Thompson and Lachlan Hansen, having delayed calls on the veteran key defenders ahead of some tough list management decisions at the end of the season.

Thompson, 31, and Hansen, who turns 29 next month, have been vital members of North's defence, but the list rebuild the club embarked on at the end of 2016 clouds their futures at Arden St.

Thompson, 2013's All Australian full-back, has missed just one game this season – through suspension in round three – and has again teamed with Robbie Tarrant to man the opposition's most dangerous key forwards each week.

Hansen, however, has fallen from favour since establishing himself as one of the AFL's best intercept marks from 2013-15. A run of niggling injuries and concussions, and indifferent form, limited him to just five senior games last season. He returned to play this season's first 12 matches, but has been overlooked since an error-strewn performance in his 150th game, against St Kilda in round 13.

AFL.com.au understands Thompson's manager, Anthony McConville of Mac's Sports, approached the Roos recently to get an indication of where his client sat in their post-2017 plans, but the club deferred that discussion until later in the year.

Hansen has not started talks with North either and his future at Arden St is also likely to be decided towards, or at, the end of the season.

When the Kangaroos ultimately consider whether to offer Thompson and Hansen contract extensions, they will be mindful of the need to create opportunities for third-year key defenders Daniel Nielson and Sam Durdin.

The out-of-contract Nielson has been blooded over the past two rounds and has shown enough to suggest he will earn a new deal, while Durdin was given a taste of senior football earlier this season – in rounds three and eight – and re-signed in May until the end of 2019.

North will be hoping the 21-year-olds can become key members of its backline over the next decade. 

To fast track that process, the Roos will want to give Durdin and Nielson more senior opportunities next season.

North could also look to trial fellow youngster Ben McKay in defence next year. The No.21 pick from 2015's NAB AFL Draft has played primarily as a key forward at Arden St, but spent much of his junior career at centre half-back.

If Nielson, Durdin and, possibly, McKay shape as the future of North's backline, Tarrant is the present. Having established himself as one of the competition's best key defenders over the past two-and-a-half seasons, the 28-year-old is the cornerstone around which the Roos will recast their backline over the next few seasons.

Hansen and, to a lesser extent, Thompson appear more vulnerable. Like Brent Harvey, Drew Petrie, Michael Firrito and Nick Dal Santo at the end of 2016, one or both could make way for North's generation next.