They say that. 20 years ahead is way too hard to predict with any meaningful features. (Does Spartan ship with JavaScript events for brain interfaces?) Really it just boils down to the fact they're starting a big browser project with a fresh slate from today.

The most a browser can really do is make the architecture sufficiently modular and extensible based on a layered architecture. The web stack has always done pretty well at that anyway and even more so with the newer low-level standards like fetch and service workers.