I think we both agree that the technologies will soon be there that enable native performance (not to mention the JVM) but I still can't see the advantage with

I think we both agree that the technologies will soon be there that enable native performance (not to mention the JVM) but I still can't see the advantage with the exception of freeing the user to run an installer, but caching assets will still be a requirement. The ability to keep settings persistent can be addressed with a traditional model in the same way as Abode Creative Cloud or the Steam client, that is to say just store them. The run from every machine claim is incorrect because engineers must tune and verify that the programs run in each browser, in much the same way as is required by conventional C++ programs. In fact, the myriads of browser, version, architecture combinations make me remember the good old days of targeting x86 Windows XP. I think the trend is very much only applicable to service startups, and against it run trends like C++11 and QT letting me build native apps on Windows and Android from the same codebase.