The NDP did not do bad during the 2011 elections under Jack Layton's leadership and 2019's as they were able to become the opposition party and negotiate some stuff when it come to passing bills (Jagmeet helped to increase the CERB payment for people that lost work during COVID). They have a solid platform but people are often caught under the loop that they're strictly a socialist/communist party etc (they'll raise the taxes on the working class to fund public enterprises).
Quite the contrary though, they're a social democratic party and can get voted out when the time comes (provincial elections have seen NDP leaderships come and go). Actually, I think they have become quite popular across the provinces since the last decade as they have secured majority gov't in Alberta, BC, Manitoba and Nova Scotia.
Coming this election time, I do think they might be able to form an opposition again if the seats are split between the conservatives and liberals. I guess when the time comes.., maybe down the road....the NDP might have their chance at winning the federal election.