I believe there will be elevated crowds on both sides. You'll have more people go before SW opens to make sure they get their trips in before the "madness" starts, which will, of course, cause its own madness. Then you'll also have the big SW Land crowds themselves, which will be more madness when that opens. Much will depend on the actual opening date, when that date is advertised, and when that falls with AP blockouts and things like that. The AP-blockout-lift at the end of summer will probably be way crazier than normal. I also bet there will be a LOT more Signature passes by then, so maybe the blockouts will not matter quite as much because a smaller percentage of APs will even have blockouts.
I also suspect that parts of the summer will be less busy than people anticipate; however, there's really no way to predict when those times will be. With the new AP structure and the number of people too scared to come, though, there are bound to be some random low days here and there.