This is one of Vox's Future Perfect predictions for 2023; they give it a 90% probability.
Sweden and Finland formally applied to join NATO in the aftermath of the Ukraine invasion, in a massive reorientation of Nordic defense policy. While Sweden was secretly cooperating with NATO throughout the Cold War, it was publicly non-aligned during those decades and often vocally critical of the West. Meanwhile, Finland was so thoroughly under the Soviets’ thumb that the USSR once forced a Finnish prime minister they didn’t like to resign.
Turkey, a member since 1952, has reservations about the Swedes and Finns related to their support for Kurdish causes, which has been delaying their accession. This means that Sweden and Finland joining is not a totally sure thing, but I think it’s pretty close. The consensus among most observers is that Turkey is trying to extract a few concessions from its Western defense partners and understands that the massive benefits the new members bring to the alliance outweigh any downsides.
Resolves according to Vox Future Perfect's judgment at the end of the year.