Eventually they will build their empire. India is full of City fans now and given superstars like Haaland, appeal will grow across Europe as well.
Like it or not, football fans are fickle.
Continuous top of the table positions + CL later stages is enough of a base to build a legitimate side.
Not a surprise.
City is most likely to attract fans from Asia, as the continent as a whole doesn't have notable history in Football, so they rather support a club from another country, especially with cable TV being very available nowadays.
In Europe, in the most populated countries (Germany,Spain,Italy, and France) you barely will find people supporting english clubs, let alone City, because they do have their own clubs and history.
In terms of pure numbers, the biggest market for all english clubs(including City) will always be Asia, due to how populated is the continent and lack of proper local football history will push asian fans to look outside.
Man Utd has massive support in the scandinavian region, but in pure numbers, they are a minority in the international Man Utd fanbase, whose most are located in the asian continent indeed.
I doubt Haaland will attract a big european fanbase for City, if it does it will be in smaller countries like Austria,Czech Republic, Sweden, etc not in Germany,France, Italy, or Spain, so in mere numbers it won't be a big increase...they are aiming for the asian market.