Thus, if we are looking at financials and discussing whether to sell 24-105 for a 24-70 f/2.8 II, one must look at the future value of the f/2.8 II if you think you might want to upgrade to that IS version in the future. And my thought is, the value will drop dramatically when an IS version is announced because people will be climbing over each other to get the IS version - look at all the recurrent threads and posts building demand for the IS version! The only way this won't happen is if Canon keeps the f/2.8 II where it is and makes the 24-70 f/2.8 IS significantly more money, though that would be unprecedented cost wise for the focal length compared to past offerings. All of those people upgrading will then dump their f/2.8 II on the used market which will greatly lower used value.
So, while you could say f/2.8 II is the only option NOW, it might also be worth considering waiting for 2014's big lens announcements as many were disappointed that the II did not have IS. I'm sure Canon would love to resell an IS version to those who bought the II, and it might be worth holding out with a lesser lens just a bit longer.
Of course if you need f/2.8 24-70 today, you need it today. But then there really isn't much to debate
Guessing Canon's next move is next to impossible, unless one has any inside information of course.
In my limited usage of Canon's products, I've come to notice that Canon is loathe to release an update that doesn't make sense to them despite their customers clamoring for it. See the people wanting more MP, more DR, an update to the 100-400L, 135L, 800L, etc.
With Canon, it's water off a duck's back. It will only be released if it makes economical sense to Canon, not because folks like you and me want it.