With a new version with "amateurish" IS and maybe replacing the 24-105 as the kit lens, the price might be oriented more towards the general dslr crowd and thus not much higher or even lower if the iq is great, but not as stellar as the non-IS.
A couple of problems with this. One, they already did the R&D on the new IS, so, they'd put it in any new lens. They aren't going to invent a crappier version..and I can't see them willingly putting on an older version to a pro kit lens.
Two, the 24-105L isn't that old a lens, and people seem to like it well enough. They kitted it with the 5dIII, and I can only really see them changing kit lenses when they release their next pro-level camera. The closest thing that would be is a new 7D, which seems to be a ways off.
And, most likely they wouldn't make the new kit f/2.8, as it would kill an upgrade path for users. People who need more light upgrade from the f/4 to f/2.8 or primes. If you're already at f/2.8, you'd only be upgrading for IQ.
They have 2x 70-200/2.8 in the lineup
Mostly though, I can't see them releasing a 24-70 f/2.8IS that is say, $1500 (or less). For most users, they're gonna take the IS version because it has IS and is cheaper. Those that read deeply into reviews might go to the mII for sharpness, but, that's not the majority of users. Now they've just made their 24-70 obsolete soon after releasing it...a $2300/lens mistake.
Plus, it doesn't match the Canon philosophy, which is that IS versions cost more...in fact, I can't think of a single Canon lens where the non-IS version costs more than the IS version. The 70-200's nearly double in price with IS; the new non-L primes doubled in price with IS, etc.
This just sort of seems like a solution looking for a problem. The 24-105 kit lens is good for what it is...no need to update it to something that confuses users.