Canada

Sure, and the Liberals have always had their entrenched numbers too.

If you believe that the entire Canadian electorate is fundamentally unchangeable, then you're basically arguing that there's no point in third parties even existing. We are doomed to endlessly rock back and forth between Cons and Libs forever, and nothing can be done about it.

True but there's an argument to be made that by the time of Layton, the NDP had already abandoned its unabashed pro-worker agenda for a neolib-lite one with social progs characteristics. Check this from 2011. It could easily be a LPC platform. Their 2006 platform was similar. Today NDP leadership campaigns talk about workers, worker rights, unions, jobs programs, democratizing workplaces, new crown corps, etc. Not saying it's guaranteed to shake workers from PP's grip, but that there's a notable shift in policy proposals and focus. That said the NDP arose from the needs of unionists and socialist farmers where the current con hotbed is so perhaps there's a chance.