The 100-400 is a must have, IMO... necessary for wildlife you're bound to encounter.
It looks like you also have 24-105... weren't you planning to take that, too? I was going to suggest a wide angle, until I noticed you show that on your gear list. If it were me, I'd definitely want wider than 50mm at times, especially for landscape shots. I carry a 24-70/2.8 instead of 24-105, but I also typically carry a 20/2.8 for extra wide shots. If you no longer have the 24-105, if I didn't already have my 24-70/2.8, for travel I'd consider the 24-70/4 IS.... smaller and lighter than the f2.8 lens... plus it has IS.
Personally I would not bother with either the swap of 70-200 for the 200/2.8, or to add the 28-300.
For one thing, a 1.4X typically works really well with 135/2, which you already have, giving an effective 189/2.8. I'd do that instead of getting the 200/2.8. As a bonus, Canon (or any other) 1.4X also will fit your 100-400. But when adding a TC image quality may be compromised (only you can say if it's acceptable) and you'll lose AF on either or your cameras (there's a trick taping up the contacts so the camera doesn't know the TC is there and will still try to AF... though in all but the best light it might be slow and tend to hunt).
OTOH, the 135/2 (although a wonderful portrait lens and very usable for sports/action too) with or without the TC it duplicates focal lengths you've already got covered... twice, in fact, with 70-200 and 100-400.
Also the 70-200/4 IS is a great travel lens... versatile, reasonable size/weight, fast focus, sharp shots (it and the latest 70-200/2.8 IS Mark II are the only two models of 70-200 with fluorite elements), plus stabilization. OTOH, there is quite a bit of overlap with the 100-400mm. Overlap isn't a bad thing most of the time, but not ideal when travelling and trying to schlep your gear through airports, etc.
BTW I see 70-300 IS USM on your gear list, instead of the 70-200/4.
50mm is a great portrait lens on crop camera, nice "standard" lens on full frame.. but it's up to you whether you need it or not. If carrying a zoom covering that focal length, you may not need it, unless you want it's shallow depth of field potential.
Same with the macro lens. The 24-105 is pretty close focusing on its own, and can be made to focus even closer with macro extension tubes. OTOH, if you are looking to do a lot of high quality macro shots, you may want the 100L.
I got a Tamron SP 60/2.0 macro lens a year or two ago, especially for travel and any other time I want to keep things compact. It replaces 100 macro, 50/1.4 and 85/1.8 lenses in my camera bag, when I want to lighten my load: one lens instead of three (all of which are as large or larger/heavier). It's crop-only, though, so would only work on your 7D. It also is a micro motor lens... not fast focusing. Fine for macros and portraits, but not for sports or any sort of action. Alternatively, Canon EF-S 60/2.8 has faster AF, but not the f2.0 aperture.
Planning to take your tripod? I'd at least take my monopod (either can usually be packed in checked baggage pretty safely, unlike most other camera gear, which I always keep with me and carry on when travelling).
I'd take my flash, too... with a flash extender for long-lens wildlife shots. Fill flash can make or break shots at less than ideal times of day, such as high Noon when shadows are heavy.
