I know how cliche it sounds, but MGSV taught me that bigger isn't always better. It was "The Ultimate Scale," "The Ultimate Story," and "The Ultimate Metal Gear" yet Metal Gear never felt smaller to me. (And oddly enough, the time it felt biggest was in a PSP entry - the one originally slated to be "MGS5.") The game doesn't have to be "open world" like The Phantom Pain was to make the most of the Fox Engine. I think that the next Metal Gear could give us several, more spacious Camp Omega-like maps and it would be just fine, because quite frankly, that's what I wanted from TPP. I just think Ground Zeroes is the perfect template for the series going forward: bookend cutscenes to start and end an act, gameplay with story sequences sprinkled in, in-depth cassette tape-type Intel distribution.
Portable Ops is canon, even Kojima himself said it. What he said is if it doesn't clash with anything in the other Metal Gear games then it counts, so his stories have the upper hand, but since there is absolutely nothing in MGSV that would invalidate Portable Ops in any way we can safely say that the entire thing is canon. Which makes me a happy panda
Ah, yeah! He just danced around it so much that I decided to label it canon regardless of what he said. But yeah, Portable Ops had a pretty engaging story and I don't feel like it conflicted with the rest of the series at all. In this universe, it's entirely possible to have a game take place at any point of the timeline and still tell a worthwhile story, so I really hope Konami/whoever leads the charge can pull it off!