I think the main browsers will continue to dominate (it's tough work to launch and maintain a browser, so there's a high bar to entry). I feel native features will continue to be exposed via the browser, and eventually, I can see web apps eventually replacing their native counterparts. I am personally a big fan of web apps, and prefer them to native downloads that highjack my phone or computer - browsers just need to be careful to manage permissions to intrusive APIs in a sensible manner.