Qualcomm is still the only ARM player to have two generations of LTE SoCs on the market. This helped Google choose the Qualcomm Snapdragon S4 Pro, a 2012 chip that is still significantly faster than Tegra 3 and that can offer an LTE at roughly the same, or very similar chip price. Besides, the APQ 8064 is by no means an obsolete chip, it is pretty fast even by today’s standards.
The US version of Nexus 7 prepared for AT&T, T-Mobile and Verizon 4G will come soon, probably adding an additional $100 to $269 price for the 32GB version, but this is a guess as we saw this trend with Apple and Google in the past. Adding 3G or 4G on top of the tablet costs at least $100 extra.
The second reason why Google went Qualcomm was that Nvidia Tegra 4 was not the perfect match, and Nvidia didn’t have an alternative to offer. The other reason was that Tegra 4 got delayed and barely started shipping in July 2013, some 6 months after it was originally supposed to ship. Tegra 3 is already in the first Nexus 7 and using a Tegra 3+ chip wouldn't make a noticeable change in performance. It also wouldn’t help on the LTE front. Google played it safe with Qualcomm Snapdragon S4 Pro APQ8064 at 1.50GHz with Adreno 320 graphics as this was a chip that was widely available for a few quarters now and it is also used in the Nexus 4.
Google didn’t go for the more powerful Snapdragon 600 that many had hoped for simply as it was over its budget. Journalists around the globe didn’t make big fuss about the price increase from $199 to $239 but having a 16GB as an entry point makes more sense than having a $199 priced 8GB version of the tablet. We still miss micro SD, something that Google never included on Nexus devices and probably never will.
Google is an internet company and wants you to put all on Google Drive or similar cloudy services, not on a micro SD that it didn’t offer with any Nexus 7 devices so far.
Since Nvidia showed a chip that might be interesting for Google called Tegra 4i, codenamed Grey, the fight for the 2014 generation is on. We are quite sure that Qualcomm will fight for this win as well, as having one’s chips in a few millions of Nexus 7 based products is quite a nice achievement.