I don't believe that. Villa were only a couple of players away from top 4 this season. Arsenal are struggling to keep up financially, and the situation at Liverpool is precarious to say the least. Man City will be up there challenging very soon and Spurs will continue to improve.
Chelsea and Man Utd don't have the monopoly on Europe's best players anymore.
I think these things work in cycle. I don't see a top 4 dominating the league in years to come. Personally, I would love a Premier League that was on a more level playing field.