-------I shoot anything I can, wildlife by preference, landscape portraits of trees and magical places, portraits of people in period/fantasy costume and other things which happen inc some charity work in low light in nightclubs (for example!).......
You would be very happy with a 6D. You'd also be happy with a 5D3, it's your money but you asked for input and I'd say the 6D will be more suited. Keep the 100-400 and the 50/1.8. Sell the 20D and 28-135 together to a buyer who accepts the possible 20D problems. Neither is worth much separately and the proceeds would do you better applied toward, f'rinstance, a 24-105 (or 17-55/2.8 ). All your other gear, sell what you're not too emotionally attached to, especially if you NEVER use it.
Don't overlook some of the nicer 3rd party lenses; newer Sigmas, RokSamBow 14.
The day the 7DII is released, your 7D will become worthless (ok, I exaggerate......but not by much). I'd sell it while you can still get a decent amount and replace it with one of the newer crop bodies if you still want crop - as in reach for wildlife. Two thumbs and two toes up on the 17-55/2.8, just get it if you're going to keep crop.
Compact camera? I'd consider one of the fixed lens superzoom types. To me, 'compact' and 'interchangeable lens' are mutually exclusive, sometimes you just want to be out and about and have a camera with you in case something catches your eye and don't need to be bothered with carrying and changing lenses.
6D+WiFi+tablet+dSLR Controller = wonderful combo, nothing gimmicky about it.