If mobile games were going to replace traditional games, they already would have, the cellphone market is already nearing replacement purchase rates.

Gaming is a huge market, there is room for lots of niches, and the quality of even a typical native indie game is way way above what a browser is capable of delivering.

Show me even one web game that is close to the quality of a mediocre graphics, reasonably expansive indie game

The web sucks horribly as a platform if you care about performance, which even relatively low power indie games do.