If you replace the 18-135 with a 200, you may encounter a number of situation X's that are covered by neither the 40 nor the 200, as you will not have a wide angle at all.I agree with you and I'm sure my lens collection will continue to grow over time. I do find that the 40 is too tight for some of the indoor shots I've wanted to take, so if I don't buy a wide angle this time around, it'll probably be next on my list.
Concerning WA, I've just bought a 17-55/2.8 for my 60D and will sell the 18-135 kit lens now. Couldn't be happier. (Not useful for birds, though.)
I don't have tele lenses so I cannot recommend any, but if I were in your shoes I think I'd rent or borrow a few of them to actually try before making a decision.