My requirements probably extend further than I initially wrote, but they are secondary to the size/IQ priority (ie: I'll need something to take underwater and probably need 1080-60p too!). Landscape has always been my niche but I'm expecting much more reportage-style and even video opportunities coming my way too.
You might be able to kill two birds with one stone and consider a move to something like a Panasonic GH4. You get all the video features you'd need while still being able to landscape work, etc. And Panasonic actually has a decent upper end lens system (certainly not L's, but very good), not to mention all the legacy lenses you can use.
I use a GH2 and Canon FD lenses for all my video work, and a 60D with various canon lenses for my photography. If I had to shrink down my collection, I'd go exclusively Panasonic because its more versatile with video. And with all the speedboosters available, you dont even lose that much by going micro four-thirds over full-frame.
To a certain extent, I'm not so bothered by body recommendations; only if it is intrinsic to recommending a particular lens. As mentioned, my primary lens is a 24 T/S L II, followed by 16-35 f/2.8 L II, 100-400 L, 100 macro. I'd never forgive myself if I dropped these in favour of some that were massively inferior.
That said, you could easily get away with a 6D and shrinking your lenses. 16-35 could be downsized surely, as could the 100-400L. 24 T/S is hard to downsize, but if you were ok losing the T/S part, you'd be easily able to save a lot of weight. Heck, the 24-70 f/4L IS would cover the 24mm and macro in one, lighter lens.