It would be very versitile; there is nothing wrong with your reasoning. Worked very well in the American West.

357/38 is about middle-ground when you toss in ammo weight and bulk vs small-to-medium game ability and would be just fine. If you want to go up considerably in game animal size, a combo in 44 magnum would do that (most 44 special factory loads are real mild, but there are some nice choices - I've actually taken a liking to the CCI Blazer stuff for some purposes).

For an extreme upgrade of the combo revolver-rifle combo idea there's the 454 / 45 Colt combo - or just 45 Colt if you reload. Or the 460 or 500 Smith (someone is bound to build a lever gun in those calibers sooner or latter)

At the other end of the power spectrum there is H&R 32 mag and 22 lr. (And the 30 Carbine, FWIW)

I suppose one could make an effective arguement for a 41 Magnum as an "optimum" combo caliber. If you like single action revolvers there are a couple of traditional choices as well (44-40, 38-40, and maybe 32-20) but upper end performance with those is pretty much a reloading propostion these days.

Anyway, not a bad idea.

Tom