The decline of Inuktut wasn't principally caused by displacement or natural population decline, but rather the residential school system that attempted to completely assimilate young Inuit (and other indigenous) kids. Children were systematically removed from their communities and sent to English (sometimes French) religious boarding schools. They were physically punished for speaking their mother language. [0]

Inuktut is mostly stable, though "vulnerable," and strongest in Nunavik (the region in the article), I suspect because the somewhat-devolved region employs it as the primary language of instruction. [1]

[0] Excerpt from the Truth and Reconciliation commission's report: http://wordalive.wycliffe.ca/stories/what-residential-school..., also https://www.clo-ocol.gc.ca/en/timeline-event/indian-resident...

[1] https://www.cbc.ca/news/canada/north/inuit-inuktitut-stats-c..., https://www.kativik.qc.ca/school-board/