+1

I have been saying the same thing for years - everything I do is cross platform! I do all my programming on Linux and use all the open source lib's I can find. Everything is cross platform (including a few that are mobile - python kivy). That takes care of the desktop. Web apps (not every customer will allow web apps), I just use what ever framework is the latest. The web is still very volatile - meaning todays web framework is gone tomorrow replaced with something better. For example Angular is a major improvement over ajax and soon polymer will replace Angular.

That said, the web will become stable some time in the immediate future and I feel that will put a nail in the coffin of the thought that a OS will matter.

Johnf