Currently as things stand, Finland most likely joins in few years. Next parliamentary election is most likely won by center-right who favors it, and president is from same faction.
It's a bit situationally dependent, if threats from Russia is seen as violent, it could change their calculus. However even center-left figures already agrees it's necessity, just not now. It could be seen as provocative.
I have always thought that Finland would be in NATO already if it was not seen meddling in middle east. It has really burned it's view among leftists.