We had a period a couple weeks ago where it rained for days on end sending our local river into flood territory for a few days. Well it's been a week and a half now and the levels are returning to safe-wading depth and flow as the river is falling about 3 inches per day. That means by Saturday it'll be easily wadeable.

My question is how this will affect the fishing? I normally do pretty well for smallmouth and some rock bass with a few largemouth thrown in for good measure. At the deepest, it'll be about 4-4.5ft.

What will the falling levels do to the fishing, and what kind of structure/cover will they relate to? I've never had conditions like these.

Torrential floods could sweep fish out, esp LMs. But river smallmouth are adapted to current and can withstand heavy flooding. They'll seek shelter along the banks, often darn shallow, and esp in cover like logjams.

Afterwards, your fish should still be where you expect to find them in the winter -avoiding current: deep slow pools, shoreline eddies, in/around cover. In smaller streams they may move downstream to larger waters that offer appropriate habitat, although there is one out-of-the-box record of bass in one river moving way upstream to winter in shallow headwaters. That's not a scenario I'd spend much time checking out but it goes to show that in nature, if it works.. it works. 

In reservoirs and tidal waters, strongly receding water often draws fish out away from banks. This can be true in rivers too as fish avoid getting stranded. But in rivers -at least smaller ones- they don't tend to have far to go before they are back in the river channel and in their old haunts. You said 4fow so it doesn't sound like there's anywhere else to go.

Yes. It will effect the fishing. You will notice fish are gonna be in spots they normaly aren't. Like normaly smallmouth like pools with slow current. They might be out the there. But you should still get fish. I'm sure of it.