Here's the thing. Most new version, as far as i know, of android are ported from the Nexus devices as these are officially from Google. So of course they would get the newest android versions first.
What makes our waiting even longer is the fact that what is released now on Nexus 5 and 7 (2013) is the Developers Preview of Android L.
It is not sure if it will be version 4.5 or 5.0 although the former has been a favorite. Also a very recent Chrome update backs this up showing the new build number as 4.4.99. Now it seems as they are preparing themselves but i'd say that we wont see a Galaxy S3 port of Android L for at least 2 more months.
Fun Fact Below:
It is believed that the codename of the new android L will be Lollypop as all the previous codenames were alphabetical in terms of the first letter and all the names were of sweet treats (with the exception of the Alpha and Beta that were the A and B):
Cupcake (1.5) (similar to the next thing)
Doughnut (1.6) (what does Homer Simpson like to eat?)
Eclair (2.0-2.1) (those who don't know, this is some kind of weird french cake-thingy)
Froyo (2.2) (some kind of yogurt combination with things on top)
Gingerbread (2.3) (kind of bread-cookie mostly eaten at x-mas)
Honeycomb (3.0-3.2) (another way of saying lots-of-honey)
Ice Cream Sandwich (4.0) (name speaks for itself. if you haven't tried this ice cream then you haven't even lived)
Jelly Bean (4.1-4.3) (some kind of candy beans made of jelly)
KitKat (4.4) (well some kind of chocolate biscuit combination also known as KitKat. It's known to be similar to the Snickers, Twix kind of candy. There are some commercials on youtube of this candy)
And there you have it. A, B, C, D, E, F, G, H, I, J, K. Next up is L (just a coincidence that the new version, for now, is called Android L? I. THINK . NOT.)
My guess is that the next codename will be Lollypop but only time will tell.