I think the point was missed...
The purpose of a 5 round non-title fight is for #1 contender matches, or the off chance of a headliner
A: to get a clear and decisive winner
B: They need to be ready for a 5 rounder in the title-shot anyways..
Randy / Machdia, not a good example, plus 3 -5 round fights in a row would be dragging it out.
Evans / Davis, pointless in the sense if somehow Davis wins, Rampage is the next in line.
While I see your point, I'd contest that Machida/Couture is relevant to contedorship status. But, like you said it's already on a relatively stacked card, so even if non-title five rounders were already being shown, it's unlikely this would be one of them.
However, I think the direction five round non-title fights will take won't neccessarily reflect on the very little amount of detail that's been released about them now, because they seem to have grey areas. I think what'll define the presence of how often we see these fights, is how they're perceived by casual fans. If people are enjoying longer fighters, it seems obvious we'll see more of them. If it's something they come to find tedious, then I think it's also obvious that they'll pick select PPVs to show them -- if not abolish them entirely.
That being said, until the casual fan base starts to appreciate the technical aspect of MMA more, I doubt we'll see too many of them. But MMA is in a currently evolving state, and so are its fans. It'll be interesting to see what this new dynamic does for fights. I for one, am certainly hopeful to get more five-rounders out of fights that could easily go that long, which is why I indicated the Machida Couture fight would be fun to see as a five rounder. I wasn't so much considering that it was already a part of a stacked PPV.