What the OP put up (written by whoever) is just stating the obvious, it's exactly the same everywhere. At school in the 80's the most popular team in Southampton was Liverpool, in the 90's was Rags. I probably knew upwards of 90% of City fans here. I was in the Wessex supporters club, run by people from Poole (close to Bournemouth) which was the closest branch, next was London. There were 4 (if i remember) including me who were members living in Southampton, 3 of us attended games. There were more City fans, mostly met by chance, but all adults, next to no kids........
But now, City tops are as popular as others with young adults here. My youngest (13) has many friends who 'support' City, we regularly go bowling/play Pool in Southampton, 9x out of ten there's is a kid there in a City top, usually 2 or 3, and it's not a particularly big or busy place. Success brings support, whether those 'fans' are long or short term.