Media commentator Bill Ralston described the announcement as "sad news".
"That's really sad news, but 3D is obviously a reasonably expensive product to make," said Ralston.
"They're in severe financial difficulty. It's a shame to see any current affairs disappear, particularly a quality programme like that one.
"I think it just forces viewers who want current affairs product back to TV One ... It looks like TV3 really is getting out of the current affairs market and leaving it to residual news programme with a 7 o'clock happy chat show."
Mr Ralston said the series - which has undergone several incarnations since it was first launched in 2013 - was not helped by a recent change in timeslot.
Originally called Third Degree, the current affairs series underwent a revamp this year, as the network attempted to stem falling ratings.
It was cut to 30 minutes and moved to Sunday nights at 6.30pm, then later to Monday nights at 9.30pm.
"I think the changing of the management was the biggest blow to it, then the changing of the slot. If you keep changing a programme's time slot, you will very quickly lose its audience. And that's happened here I think," Mr Ralston said.
In a statement, Mediaworks head of news Mark Jennings said: "Long-form current affairs is challenging to make commercially viable all over the world. Given the way media consumption habits are changing, unfortunately continuing 3D may not be possible."
Consultation with affected staff is underway.
Hosted by Samantha Hayes, the programme is home to many of TV3's most senior and respected journalists including Penfold, Eugene Bingham, Sarah Hall, Melanie Reid and Phil Vine.
NZoA had not officially commented about the timeslot change but it was understood they were unhappy with the scheduling move, which saw a massive decline in ratings.
Monday night's episode saw 87,000 viewers tune in, according to Nielsen.
Mediaworks axed current affairs show Campbell Live in May this year, after a six-week week review period which saw ratings climb and fans take to the streets to protest against the possible cancellation.