Following up on this post, there doesn't seem to be much prospect of the Cons making any effort to pursue proportional representation as an alternative to a ranked ballot if Tasha Kheiriddin's latest reflects their' thinking. But I'll point out that there's reason for the Cons to give the option a second look even if the Libs have made up their minds.
It's absolutely true that a ranked ballot system will tend to favour a party positioned on the middle of the spectrum. And the exception on a single-election basis will arise only where voters are so disgusted with that one party that they drop it from the top of their lists and/or move it to the bottom (behind competitors on all sides of the spectrum).
In other words, the prospect of limiting the Libs' hegemony under a ranked ballot system depends on a national mood where people of different values can agree at least somewhat on the need (and reasons) for change. And multi-party agreement that the Libs have rigged the electoral system in their own favour in a way that's unfair to all other parties might offer the only plausible basis to get there in a first Trudeau term.
For that reason alone, the Cons would hurt themselves as much as anybody by sticking to an inflexible and exclusionary position, rather than looking for some common ground with other parties. But the longer the Cons operate as if they were still in power today, the more likely they are to be stuck with a system that keeps them away from it in perpetuity.