As others have mentioned, i honestly don't think they'll get rid of siri on the 5C. I guess they're going for the same market as the 4s thats still for sale. Younger teenagers that want a phone, but can't get the 5. I suppose its just a "lets make the 4s look different to the 5, give it some colour, oh, and it'll be cheaper to make".
Except that if all of the leaked pics are correct (and you know half of them at least probably are fake), the 5C or whatever it's called has the same larger screen as the 5. So it might share some parts from the 4S but it likely has mostly 5 parts in it.
It's going to be odd. If they price it too low it's going to eat a ton of Apple's margin on the 5S. If it's priced too high it doesn't make a lot of sense to release it here (in the U.S.). A huge part of Apple's iPhone hardware profits are the enormous subsidies the contract carriers pay Apple on every sale. On the other hand, Apple can reason that the iPad mini might have eaten into full size iPad sales, but at least those were still Apple sales.