Really? do you think the older 35 will become a desired, somewhat unobtainable lens?
Nope, but after the first enthusiasm over the 35L2's stellar quality people will realize that for many, the ol' 35L1 is "good enough" and the successor isn't worth an additional $1000 = more demand for 35L1 = higher price for quite some time (look at the 24-70L1's price curve).
Do you think this still be the case, if the new 35 will not be considerably more expensive?
Looking at Canon's pricing policy, they either try to sell something unique like the IS primes or extremely high iq items like the 24-70L2 - I don't expect any upcoming reasonably priced L "workhorse" lenses anymore, for that you have to look at Sigma I'm afraid to say. But there always will be enough people demanding Canon, even if for cps alone.