My understanding is imperfect to say the least, but from what I gather with these mixed member proportional ones is that this is, essentially, how a number of them operate anyway. I think Germany and New Zealand would be a couple of places where you have x number of people who were elected to represent districts, but then you have others who were elected from a general list, which I presume is on a regional basis, and that would make sense. You could have a Parliament with 338 members where not all 338 are from a defined district in the same manner they are now. You could have some from that form and some from a list. You could have dual seats where one of the members runs in the riding and one comes from a list. There are any number of possibilities, but I think if the outcome is that the legislature reflects the vote of the people, then I think that's the fundamental goal.
On October 5th, 2016. See this statement in context.