We play two nights a week, sometimes one. We had 3 weeks where lag was unplayable in Naxx... so we have only had Naxx full cleared for 2 weeks. Given those odds as casual yet capable players, things like these mounts will always be out of reach. 4 more weeks of gearing up may be enough, but I am guessing it very unlikely -- especially with teh Sarth+3 requirement that alone will prevent most 10 man (only) guilds from accomplishing this.
Unless you raid every other week, you have virtually the same single clear every week to accomplish things that everyone else does. Also keep in mind, it'll probably be at least another month before this is released.
Again I see the reasoning, just disappointed.
The beast is getting hungrier.