She is currently signed with the South Auckland-based Northern Stars in the ANZ Premiership, though that contract ends at the end of the current season.
If she was to make this year's World Cup squad, Cullen would join Johnson in Sydney after the July tournament.
It's unlikely she would miss out on the event because of form as she's one of the best players in the country in her position, with it more likely to be because of injury.
With 47 tests to her name, the 27-year-old has been plagued by injuries, restricting her chances in the black dress in recent times.
A serious knee injury, which resulted in invasive surgery, kept Cullen out of the Silver Ferns and last year's Commonwealth Games campaign.
But when fit, she is a perceived starter in any side, and would be a valuable asset in the Silver Ferns for this year's World Cup in Liverpool.
If Cullen was to eventually sign with an Australian franchise, she would need to seek exemption from Netball New Zealand to remain eligible for future Ferns selection.
A player can't play outside of this country and be selected for the Ferns.
However, she wouldn't have to look far for examples of players flexibility with that rule.
Current Silver Ferns captain Laura Langman is playing for the Sunshine Coast Lightning and has been eligible for the Silver Ferns, while veteran shooter Maria Folau this season joined the Adelaide Thunderbirds and will also be allowed to represent New Zealand.
Cullen, though, reportedly hasn't decided her 2020 plans, and is keenly focussed on the current New Zealand domestic season.
She's played a leading role with a Stars side which currently sits third on the ladder with six wins from 12 games.
They have an eight-point buffer over the fourth-placed Waikato Bay of Plenty Magic with three games left to play.
Silver Ferns goal shoot Grace Nweke speaks about the Constellation Cup series and the rivalry against the Diamonds in the final match. Video / Alyse Wright