You would think so. The thing that stands out to me is that we still haven't seen a single device on the market running a Samsung Exynos SoC with LTE support. I don't think that is a coincidence. The Galaxy Tab 10.1 which has LTE is running a Tegra2. Samsung's soon to be released Galaxy S II LTE is rumored to use a Qualcomm SoC.
All of this evidence suggests to me that it isn't currently possible for Samsung to release an LTE-capable device based on the Exynos SoC. No matter how awesome ICS is, that is disappointing to me.
Not quite so simple. Most processors and modems work fine together in your computer, to use an analogy. But what many SoCs attempt to do is integrate the radio within the SoC. Qualcomm does this with thier Snapdragon, which is why it is so popular. Other devices have to use external radios.
Most 1st gen 4G radios are pretty thick, which is why I think Samsung didn't integrate them in the SGSII. But newer designs are becoming available that are thinner. Motorola developed thier own 4G radio in house, and was first used on the Bionic. With the new RAZR, you can see how they made it pretty thin.
It's this same thought that the GNex will have a 2nd gen 4G radio, and will be similarly very thin. So in summary, I don't think there are any technical issues, just the realities of what's available, what pricing they get, and what level of performance they are aiming to achieve. Couple that with the fact that the design-in of a particular chip has happened over a year ago.
To reiterate this point, the TI OMAP 4460 only started sampling early this year (Q1). We aren't going to see products until Q4. Design and testing take time, and by the time you've designed something in, there's something better right around the corner.