The problem is Ted that there is now two generations who grew up knowing that every time they turned the sports channel on, the rags, liverpool, arsenal and latterly chelsea were going to be on.
Slowly but surely, they chose a favourite for whatever reason, and on the whole I reckon many have stuck with what they've known in the last two decades despite what we say about glory hunters, the rags won the league 2 seasons ago and still have some world class players (allegedly) and Liverpool incredibly seem to retain their following despite being shit.
Added to that, once you have a generation watching the rags, the kids have got some connection to affiliating themselves with the rags, or they subconsciously just grow up rags.
The only ones globally who will be turning in the telly now specifically to watch city are those who change their team as often as their underwear who are worth fuck all in terms of revenue long term (and I reckon there aren't as many as these as we would expect), and new fans to football. We might get some pockets of fans in Argentina interested in the Argentinian players, but when the players leave, some will stick with us, the rest will watch their football elsewhere.
In a couple of decades, if United win nothing and we win loads, we might be somewhere close to catching them.
There is only really one way to accelerate that