According to Crusaders chief executive Colin Mansbridge, a deal with Robertson will be reached soon.
"It's not far away," Mansbridge said when asked when the 46-year-old would recommit to the 12-time champions he first joined with forwards coach Jason Ryan in 2017.
Ryan on Wednesday extended his deal with the red-and-blacks through 2024.
"We've worked together for a long period, and we've got a relationship that's really honest. We're both very different, which is probably why it works so well," Ryan said of Robertson.
In March, Robertson said the developments around the controversial Silver Lake private equity deal would be "a pretty important part of re-signing".
The offer, which would see the US investment giant buy a 12.5 per cent stake in NZR's commercial rights for $387.5 million, has split NZ rugby in half - with NZR and the New Zealand Players' Association remaining at loggerheads despite weeks of mediation.
"It's pretty clear; if I sign a couple more years, I'll have done the Crusaders for seven years - which I love doing - but what does it mean for the next step after that? How does that line up around the 2023 World Cup if this coaching group stays on? So, there's a lot of things going on; a lot of answers to come back," Robertson said.
Ryan, meanwhile, will line up against Foster's All Blacks twice later this year.
The former prop is an assistant coach with fellow Kiwi Vern Cotter's Fiji, who face the All Blacks in Dunedin on July 10 and Hamilton on July 17.
Ryan was coy when asked if he has considered the possibility of linking up with Robertson at the All Blacks in the future.
"That's all out of my control, and our control, what happens there.
"I'm excited by what's in front of me for the next three years, and whatever happens and any decisions made at the end of world cup cycles, we make those decisions then."