Great article. I couldn’t agree more about the challenge of progressives parties splitting the vote on the left. Conservatives faced the same kind of challenge when the PCs and Reform still existed. It took years to “unit the right” and give them the advantage that they have now. In the years that come the right will have an advantage even in a proportional representation model; barring a “unit the left” movement of some kind either in the form of parties coalescing or an increased willingness for post election coalition.
All that said, I suspect that your hypothetical proportional representation seat count would have changed dramatically without the influence of strategic voting. Has anyone attempted to estimate what the proportional representation would have looked like without strategic voting?