The hot LTE topic of 2014 that made it into live networks certainly is Carrier Aggregation (CA). Agreed, there aren't too many devices that support CA at the end of 2014 but that's going to change soon. In the US, quite a number of carriers have deployed 10 + 10 MHz Carrier Aggregation to play catch up with the 20 MHz carriers used in Europe already. In Europe, network operators will use 10 MHz + 20 MHz aggregations and some even 20 + 20 MHz for a stunning theoretical peak data rate of 300 Mbit/s. So where do we go from here? Obviously, aggregating 3 bands is the next logical step.
And it seems 3GPP is quite prepared for it. Have a look at this page which has an impressive list of all sorts of LTE carrier aggregation combinations and also shows for each in which 3GPP spec version it was introduced in the specification.
For Europe, especially the 3A_7A_20A combination (20 + 20 + 10 MHz) is interesting as there are network operators that have spectrum in each of these bands. Peak data rates with 50 MHz of downlink spectrum, which some network operators actually own, would be 375 Mbit/s.
For North America, there are literally dozens of potential combinations listed. Not sure which ones might actually be used. But I suspect it will be difficult to come up with 50 MHz of total aggregated bandwidth in this region, so Europe will continue to have an edge when it comes to speed.