We are a crowded country. There is a population of 85 million. There are 9 Istanbul teams in the league. Currently, there are no teams from the top 5 cities such as Izmir and Bursa in the Turkish league. Izmir is a city of 4 million, Bursa is a city of 3.5 million. Super league matches are not played in 15 of the 30-40 largest stadiums in Turkey. If we reduce it to 16 teams, the lower divisions may become stronger, but the pleasure of watching will end. Currently, only half of the top 10 clubs of all time in Turkish league history are playing in the Super League.
If I were to design a league artificially, I would swap at least 8 teams out of 20 in the Turkish league with important teams in the lower divisons. If we reduce the league to 16 teams and 9 Istanbul teams are in the league, I think football in most cities will disappear.
The clubs in London are big clubs and have fans. 3 of the 9 clubs in Istanbul are the 3 big clubs, the others are clubs that have very few fans and consist of players preferred by football players who do not want to live outside Istanbul. Başakşehir and Kasımpaşa have stadiums, but the others either play in the Atatürk Olympic stadium or play in small neighborhood stadiums. The matches of Eskişehirspor in the amateur league are played in the new and modern stadium with a capacity of 32,500 people and in front of thousands of people.
Erzurumspor, located at an altitude of 1850 meters in Eastern Anatolia, can have more spectators than the smaller teams in Istanbul at -13° temperature at noon. Their stadiums have a capacity of 25 thousand. İstanbul domination isn't realistic except 3 big teams.