From the Nexus 7 LTE purchase page, we have the following:
E-mobile band 3 (1800MHz) not currently supported.
I have no idea how to interpret the word "currently" in this sentence. It could mean that this current hardware revision is incompatible, and if you buy it, you'll never have the option of emobile LTE. Or, it could be that there is currently a firmware incompatibility that a future OS update will fix.