Being last week in Boston, for a Novell desktop team meeting, I met some people from SuSE, including Duncan MacVicar from Chile (hard to know he is from Chile with that name :-). Very nice guy, and while being KDE people, with lots of ideas and plans that mostly matched mine. Mainly, Duncan and I agreed in that KDE and GNOME should be seen as different frontends to the Linux Desktop, and this Linux Desktop should be a complete set of specifications, interfaces and shared storage data for both frontends. We talked about some things that could be shared, like addressbook and calendar data (and concurrent access to it) and Will Stephenson, another of the SuSE guys I met last week, told us about his plans to add an evolution-data-server backend for KDE, for live data sharing.
Things like Freedesktop.org should have more influence on both GNOME and KDE, so we should try to push for more specifications there. Once we have a shared infrastructure, 3rd party developers would choose one or the other based on the same reasons people choose Visual Studio/Java/Borland/.NET/etc to develop Windows applications now, and users would choose one or the other for whatever reason they feel like.