The 26-year-old remains the most expensive player in Tottenham's history, having joined for €62m (£53.1m) from Lyon in the summer of 2019.
However, Ndombele has failed to justify his hefty price tag since touching down in North London and has been sent out on loan twice, firstly to Lyon for the second half of the 2021-22 season.
Les Gones possessed the option to re-sign Ndombele for the same €62m (£53.1m) they received for him in 2019, but the French giants unsurprisingly decided against triggering that clause, and the midfielder subsequently joined Napoli for the 2022-23 campaign.
The former Amiens man left the Stadio Diego Armando Maradona as a Serie A champion, scoring two goals and providing one assist in 40 matches in all tournaments, but he started just eight top-flight matches.
Ndombele is now back at Hotspur Way for pre-season training, but having consistently struggled to perform over the past few years, a parting of the ways this summer was seemingly inevitable.
However, Ndombele's contract still has two years left to run, and Postecoglou lauded the midfielder as a "very talented player" during his first press conference on Monday afternoon.
"Yeah, Tanguy has been good. He is working hard at training, to be fair they all are, they have got no option," football.london quotes Postecoglou as saying.
"Again, I take things as I see them. For me, he is obviously a very talented footballer, he was part of the team that won Serie A last year and within that context, I am pleased to have him here and part of the group.
"What that means long-term, again I will not get into the definition of that because a lot of that will depend on how the team shapes up and how he shapes up.
"He may decide this is not for him. I'm not sure. Like I said, the group I have had in so far have been really good at embracing the change of direction, the way we are doing things.
"As I said, once we get all the other guys in, it will be great to see how everyone measures up and decisions will be made moving forward from there over who will be involved and who won't."
Ndombele has amassed 10 goals and nine assists in 91 games for Tottenham since his record-breaking move, but he has not played for the club since an FA Cup win over Morecambe in January 2022.
Tottenham currently have Yves Bissouma, Oliver Skipp, Pape Sarr, Giovani Lo Celso and Pierre-Emile Hojbjerg as their fit midfield options, but the latter two are being linked with exits, while Rodrigo Bentancur is still on the long road to recovery from his ACL injury.
Postecoglou was also quizzed on the Harry Kane transfer saga in his opening press conference, and the ex-Celtic coach admitted that he had received no assurances over the 29-year-old's future.