I am a bit biased, as I do have the 6D and have not used a recent digital Nikon body. For landscape and nature (excluding fast-moving wildlife and birds), an 11-point AF system is fine. In fact, I tend to manually focus most of the time with landscape, all of the time with macro. Dual cards I don't care about, as I have not had a card fail, and I am not shooting professionally where even an 0.01% failure, if it happens to you, can be a reputation killer. Most of the time when I shoot landscapes with the 6D I am working on a tripod and am using live view, and the live view implementation on the 6D is good and one can shoot from live view (which is the equivalent of mirror lock up). The low light performance of the 6D is very good, and this matters to me because I like to shoot astro-landscapes. I would like more dynamic range than the 6D possesses. I don't know how the Nikon 610 rates for DR and low light use. I have started using graduated neutral density filters, to supplement my other strategies of post-processing gradient-making.
There are a lot of options for macro for Nikon, both new and old Nikkor lenses, and some very good third party lenses by Tamron and Sigma. In theory you could try to find an adapter to fit your Canon to a Nikon mount, but you would lose infinity focus and electronic communication to the camera. My Canon macro is the EF 180 f/3.5L - I like long focal length macros - both for the bokeh and for the distance separating me from shy (or venomous) critters. The Nikon equivalent is the well-regarded 200 f/4, which is an old design about to be refreshed - but that means that a lot of copies will be hitting the used market soon.
I love the Sigma 35mm f/1.4 Art. Great landscape lens, and decent bokeh for when you want to shoot at f/1.4. Splendid for astrophotography. This and the tiny (and cheap at under 200 bucks USD, and dam' sharp) 40mm f/2.8 STM are the "normal" lenses for my 6D. The 40mm f/2.8 STM is inconspicuous and might be better for "street" than the Sigma f/1.4. I haven't yet bought a modern 50 to 55 mm lens for it, but have some legacy manual Nikkors and Mamiya-Sekors that I use with adapters.