Yeah, and when was the last time City, Spurs and Liverpool won the league? It's been a while since Arsenal did too. Chelsea are falling to pieces and an admittedly weak ManUnited team has been dominating the league in recent years.
The only team that looks like maybe snatching the title from United this season is City, and they still look like they won't.
Also, to say La Liga will always be dominated by two teams is an unrealistic expectation. Real Madrid and Barcelona are statistically I believe the most successful football teams in the world, but there have been quite a few titles that went the way of lesser fancied teams.
It's also funny because realistically, only City and United can conquer the EPL.
Do you seriously think that with City's money and United's consistency that any of the other four teams are truly capable of winning the league? They might have more chance than the other La Liga teams do but it isn't by much.
Also, when you consider the current Barcelona team, seen by many as the best football team ever seen, play in that league alongside the richest club in the world, it's hard to think but correct that other teams have a chance; both Madrid and Barcelona can't keep it up forever.