If I am the Liberals today, I would be giving serious thought to electoral reform (cue hoots of derision) even though that inevitably means proportional representation.
The broken 2015 promise was always going to stumble over Trudeau's interest in getting some form of ranked ballots - versus the NDP and Green preference for some form of PR. The self-interest for the Liberals is obvious, as a party of the middle is apt, all other things being equal, to be the 2nd choice of voters to the left of them and to the right of them. But that is even more of a non-starter in a minority parliament than in a majority. I believe that PR may now be in even the Liberal Party's best interests, while also benefiting the NDP and Greens.
As I look at the map today, I see little prospect of Liberal majority government any time soon. Atlantic Canada has returned to something like political normalcy, with a Liberal edge and the old loyalist New Brunswick ridings returning to the Conservative fold. The Liberals are completely shut out of Alberta and Saskatchewan and rural Manitoba. The three-and-a-half way split and the geography of BC, shows that the Liberals are never going to get numbers above 20 and typically closer to 10.
At 157, Liberals need 15-20 more seats to have any prospect of a durable four-year majority. The only road to that lies through an even more lopsided result in Ontario or through Quebec outside of Montreal. But the return of the Bloc has scooped the best opportunity for those Quebec seats as the NDP waned there. And the Conservatives' total of 10 shows that they are pretty well entrenched in East Quebec, despite a piss-poor performance from Scheer. Only a fool would be betting on prying the Bloc (now funded as an official party) out of many of their seats.
Strategists talk about "paths to victory" and I see the Liberal paths to majority as being as few and remote. So in that crass political calculus, I might prefer results under a PR system where I hope to be the plurality party much of the time and the plurality party among the centre-left and left the rest of the time.
There are lots of issues to address on the path to PR but I think you might well find some converts among Liberal pragmatists.