The web is now hamstrung by the HTML/CSS layout model more than anything else. The hackery required to attempt to imitate native mobile apps is horrific. Google would be better off throwing efforts into a new layout engine leveraging raw JS and WebGL, but with a sane API, than these continuous attempts to push HTML into places where it doesn't work. If they don't lead it I can see someone else doing it in such a way…
In particular, the broken implementation of CSS position:fixed on all mobile platforms is probably the major stumbling block preventing app-like interfaces for the mobile web. I have been frequently tempted to try to build a canvas-based interface from scratch, but I suspect even that would run into the same problems.
For all the talk of web apps as credible alternative to native ones, the fact is the current toolchain is unlikely to ever be good for anything more than paper-thin clients. Ecmascript 6 doesn't fix this, Ecmascript 7 won't fix it. HTML5 tags are a worthless collection of semantic sugar when we desperately need a solid component library instead of implementing everything from scratch.