I think your general misunderstanding is that JSF 2 and HTML 5 are seperate technology stacks and this doesn't have to be the case. JSF 2 is a specification for server based lifecycle, server side events and streamlined Ajax based web controls. In this way it is similar to ASP.NET. There are many different implementations of this (Eg. Mojarra, MyFaces, etc...) and these can in turn be supplemented by third-party component libraries that enhance the control set (Eg. Primefaces, IceFaces, RichFaces, PrettyFaces, etc...)
A JSF component will be defined by server side code but renders to HTML markup on the web page. This means that JSF components can render HTML5 and there are real examples of this: http://www.primefaces.org/showcase/ui/fileUploadHome.jsf
So there is really nothing to "convert". One can create a custom or composite JSF component that renders any HTML5 content that you desire.