Trying to be more helpful this time, that's a really good question from Sara.
I think mixing formats is very difficult, and you've got quite an investment in crop format lenses currently. It messes up all your focal lengths.
If you could just use the 7D for long lens stuff and action, which is the only thing it does better than a 5D2, then you might be okay with a couple of lens changes, eg 17-40L and 24-105L/24-70L, but otherwise there will be a lot of overlaps and possible duplication. On the other hand, how often do you use the long end of the 100-400L? If it's not that often, on a 5D2 maybe that could effectively replace the 70-200 on a cropper, if you see what I mean.
Not the same thing for sure, but the range would be similar and you could just crop your way out of it when you run out of reach. It's those sort of difficult decisions and compromises that you have to sort out. Not easy.
Be aware that once you see the IQ from a 5D2, you'll want to use it for everything. That's what happened to me