I still think there is a long-term desire to "build once, run everywhere" with a certain class of software. With decently fast Internet access becoming ubiquito

I still think there is a long-term desire to "build once, run everywhere" with a certain class of software. With decently fast Internet access becoming ubiquitous, the web browser became the simplest delivery mechanism for that kind of software, which I think resulted in the explosion of "web applications" over the past decade. Granted Java tried to create a VM that's "build once, run everywhere", and for the most part it succeeded and is still strong today. It can also be relatively straight forward to build and compile in C everywhere something small and simple as long as you use portable libraries. But in both cases the delivery and update mechanism is not as easy as: type facebook into your browser's address bar and press enter. ActiveX, Java applets, Flash, and Silverlight all failed to take off (Flash had more success, but mobile has since killed it off) for building applications. Why? I've used some software built on Adobe Air and I've found that to be a fairly pleasant experience. What can we build that gives the benefits of a browser-based delivery, but is better than HTML/CSS/JS?