Interesting point Cowlitz your right i am sire that has never been studied and I am just as sure that it will never be studied. I don't know if there is any merit to the theory but even if there is BPA NWPPC and the ACOE certainly don't want to know about it.
About dam removal, The dams will someday come out they will not last forever concrete ages and crumbles so eventually they have to come out. By then i am sure it will be far too late to do anything to save the fish. As far as the flood plane goes, I am certainly not an expert but my theory is that without the dams although the river would fluctuate more the river overall would be lower. I believe the river to be unnaturally high even during low flows because of water storage. In the winter when flooding occurs there will be no water coming from the eastern side of the state and the rockies so the only areas prone to flooding would be from Portland down but at that point the water would already be so low that no flooding would occur. The Columbia would also be flowing so hard that it would no longer cause the Willamette to back up as badly. The Columbia would reach it's peak flow in the late spring when the snowpack in Idaho and Montana are melting (june July).
I think the removal of tributary dams would show GREAT promise for fish restoration. Imagine what the north Lewis was like before the dams went in, and the cowlitz. if we had thoes rivers in pristine shape? No one would ever go to Alaska to salmon fish or to BC to steelhead fish.

Anyway thats what I think based on nothing but my own opinions and theorys i may be FOS but who knows