Think of it like the S4 vs the S4 pro. It's gonna well into the second half of the year before we see any Snapdragon 800 phones, methinks. The Galaxy SIV will feature the S600. But the One X/GSIII were still very fluid even with the "lowly" dual core S4.
The S4 was considered a beast when it was unveiled several months before the HTC One series and Galaxy S3 emerged. The only complaint was a slightly under-powered GPU. I think it's the exact same with the Snapdragon 600 with Adreno 320. It will be great, but it will quickly lose appeal as Apple's new SoC and the Snapdragon 800 are in products only a few months later. Unfortunately, even the Adreno 330 GPU (which is a 50% graphics performance increase over the Adreno 320 in the Snapdragon 600) is said to fall short of the already old Apple A6X from last year.
That being said, the S4 in my Galaxy S3 is still quite fast and I'm very happy with it even today. Upgrading to the Snapdragon 600 is said to be a 40% increase over the S4 so that's already amazing...and I am definitely a believer in real world performance > specs on paper. Unfortunately, the tech world loves specs on paper...and I would rather wait a few months extra to get a HTC One or Galaxy SIV with a Snapdragon 800!
I think you will see more snapdragon 800 in tablets as the power and performance is ridiculous, if any body has heard that rumour of the new nexus 10 or new nexus 7 then they might feature a 600 or 800 and google I/o is in may. That then Gives google time to use the latest hardware.
I think Qualcomm made it pretty clear that we should expect the Snapdragon 800 in phones as well. I have now seen that they don't expect it to be available until the 2nd half of this year though...so it probably won't make it into the Galaxy SIV. I agree Google would be quite happy to one-up everyone (except Apple, again) by releasing a new Nexus with the Snapdragon 800...it's just too bad they probably will skip on LTE again...that's the only thing holding me back from my desire to go pure-Google.