I'm thinking, from all of the responses weighed against my innermost agonizing, that I don't really use the 135 a ton even though it's FLAWLESS when I do (and I rarely go below 2.8).
And that my 16-35 and 40 pair nicely so a 70-200 might minimize my "need" for a 50; also in light of having the ultra-mega-convenient 40.
So saving $1300 from not buying the 50 and selling my 135 would exactly pay for the 70-200 2.8 IS II and would probably use it a lot more than my 135.
With that, I say "****", and probably very maybe do it immediately.
In conclusion - 16-35, 40 and 70-200 a good kit? I had also mentioned the 100-400, but I almost never really need 200+ (having rented one twice and it was glorious, but infrequent).