Canon is good at lenses, and not so good at sensors. Unfortunately I don't think sensor performance will be at Sony Exmor level in the coming generation of Canon cameras. The typical user don't care about sensor quality differences, since the different manufacturers are close enough to each-other, so I don't think Canon is very pressed to be on top.
Sensor-wise for the landscape photographer Nikon D800 seems to be a safe bet. I'm heavily invested in Canon lenses and when it was 5Dmk2 vs D700 it was sure better to have the Canon resolution despite slightly less good DR, but 5Dmk3 is rumored to be 22 megapixels and if the trend continues the DR will probably be slightly worse than Nikon's (Sony's) D800 36 megapixel (especially considering pattern noise, an artifact that dxomark does not measure but greatly reduces the subjective "photographic DR"), so then you have a camera with less resolution and less DR, at least at ISO100.
If I would invest from scratch today, it would be a really tough choice. I prefer Canon for the lenses, but Nikon for the sensors (D7000, D3s, D3x, D800).
Based on loose rumors there is a chance that Canon will introduce two new bodies this year, the all-around 5Dmk3 (faster than D800, but less MP and probably a bit less DR at ISO100) and another "Cinema DSLR" which actually may be very high res in stills mode. DR will in any case be less good than Sony Exmor - Canon simply does not have the technology to compete - that is I don't think that they choose to prioritize other things, they simply can't do it at this time even if they wanted to. However, differences are not huge, it is more of an irritation when one sees the noise and knows that competing products are better rather than it is a practical problem in making images. In the cases I use HDR techniques I would need HDR also with a Sony Exmor sensor, I don't think my workflow would change with 1 extra stop of photographic DR. So for me personally I'm more worried about Canon possibly not being competitive with resolution than DR, as long as they don't move backwards on that.
Some of the Canon lenses seems to scream for higher resolution sensors though, and the new 24-70 they seem to prioritize high resolution ahead of image stabilization, so I would be surprised if Canon will not come up with a 30+ megapixel body sooner or later, but it may be in a costly pro package (will make 1DsIII pro users happy, but not cost-sensitive 5Dmk2 users), and maybe not this year.