Publishing on the web and on paper are two very distinct processes that constantly create headaches for publishers because they are so hard to get right. There is InDesign or TeX or certain XML on the print front, and then there is HTML for web. Conversions between one and the other are hard to impossible.
There have been some initiatives to try to bridge the gap in the past. There are some closed solutions to convert HTML to print PDFs, such as PrinceXML and AntennaHouse. But their input format was not standardized, styling worked somewhat differently and because only a few groups used them, they could never turn into standard solutions.
There were some efforts to add paginated media to web specifications, but with the exception of Opera, none of the browser makers thought these specs were useful enough for their users for them to implement.
Also some, such as myself, tried to build a web based layout engine on top of existing and experimental browser technology. But the result of these efforts were limited by the fact that browser technology wasn’t really made for what I used it for.
In 2015, it is my believe the Vivliostyle team will make a strong effort to change all this. Vivliostyle will both want to be involved in the discussions on W3C standards and build open source webbased typsetting tools. It is this combined effort that hopefully will bring about the change that will make publishing on web and print simultaneously much easier. I am looking forward to working with Vivliostyle to make this happen.