I doubt that most would kill the space in a 28" can for an M1 install....you can really put a very large system in one of those units with SWG's, even considering dead space for cabling. The only items that start taking up space is maintaining the bend radius for an ethernet cable on an XEP and then the same for XSP's and their DB9's. I can speak for my own house, with literally everything wired, multiple distribution points, 2 power supplies, batteries, etc, with a pair of 28" cans piped together for my M1, I'm still swimming with space.
Even putting a whole house's structured cabling and patch points in a second (or third) 28" can, I doubt that most would ever be able to run out of room, as long as wise choices were made for modules to be installed inside.
A giant single can looks good on paper until you start factoring in all the cable entry points and the volume of cables that'll end up inside of it, your working room ends up being close to nil at some point.
While it may end up being in the realm of tin foil hats, I personally don't want another trade (CATV, Telco, etc.) in the same enclosure as where my security panel and wiring is, there's just no need for it IMHO and too many people within those trades end up touching things they either shouldn't or they don't understand how it works (not knocking them, it's just not within their scope and world).
While unrelated, we had a house that was fully roughed and run to enclosures with CCTV and security in one and structured in another. Even though the agreement was for them to provide service to the enclosure, no further, and get the STB's working, the CATV/Telcom tech took it upon themselves to land every cable in our security cabinet to punchdowns and splitters, cutting all the cabling "right and tight" with no slack. They were really proud of their work, until we came in to finish our end and none of the cabling would reach to any connection or device within the enclosure.