If this rumor is indeed true (which we don't know yet), I think it can only be positive that there will be so many good options at 35mm: the new Sigma, the current 35L (aftermarket once the 35L II goes on sale), the 35L II, and for those that need IS, the 35 IS.
I have to say, though, that I would have been happier with an announcement for a 50L II or a 50/1.4 II. That's where I feel the Canon line-up needs more attention.