The midfielder was taken off at half-time of Spurs' win over West Ham on Saturday, which led Cascarino to question the Tottenham star's role at the club under manager Ange Postecoglou.
Postecoglou was spotted pointing to Pape Sarr to tell him he was coming on for Maddison who, despite providing the assist for Dejan Kulusevki's equaliser, was disappointing throughout the opening half.
Cascarino now believes Maddison is in danger of losing his starting spot as he spoke to The Times about how the 27 year old will be watching his performance back and reflecting on it.
"He (Postecoglou) has put the challenge of changing Tottenham ’s mentality and notoriously soft centre on his shoulders. I liked that he was prepared to make a big call and withdraw James Maddison at half-time," Cascarino said.
"It would have sent a message to every player that their place is not assured after the Brighton debacle. Maddison was a big signing last year and I have no doubt he would have taken the timing of the substitution personally. Postecoglou can manage the situation.
"But Maddison may reflect on his delivery, especially from corners, and work rate. Maddison is no longer a promising young player. He turns 28 next month and needs to impose himself on matches. He finds himself out of the England squad and his starting place for Spurs is no longer guaranteed."
Postecoglou opened up on the decision to replace Maddison, which he says was about controlling the game and winning the midfield battle.
"We needed more running power in midfield and Pape (Sarr) has lots of that, bags of energy and running. He really helped us to get control of the midfield and that gave us a good platform to go forward," Postecoglou told Match of the Day.
"Our general play improved from there and we looked dangerous going forward. We knew there had been a bit of an arm wrestle and we always back ourselves to keep going at the intensity we always do and upping it and taking the game to West Ham.
"We knew that putting them under pressure here at home we would eventually get there. We had to fight hard in the first half. Going a goal down wasn't ideal but we clawed our way back into it, and it is not easy.
"Second half we were outstanding. We upped the tempo and played some quality football, defended when we needed to and got our finishing right. We want to be that sort of side that creates lots of chances."