I asked on the U-Boot mailing list for a roadmap to current/upcoming architectural changes, and Lukasz Majewski was kind enough to point me to some sources of information.
Please look into ELCE2014 slides from u-boot mini summit at Dusseldorf (slides are available at denx.de webpage). There was a presentation from Simon Glass regarding device model road map.
There will be u-boot Mini Summit held at ELCE 2015 in Dublin. I think that the road map issue is a good topic for our overall discussion panel.