That will be difficult to do, since the next generation of 5G mobile products will not be introduced for another 5 years or so. Our crystal ball is good, but not that good.
See this article: http://en.wikipedia.org/wiki/5G
Perhaps the ATT "tech" was thinking about something else? Or, you may have misunderstood what he said?
As far as products that are available today, a store bought modem or modem/router will not provide any faster service than your provider can send to you. So, for example if your current Internet connection speed is 12 Mbps......about what ATT offers at the present time as their top tier plan......a new store bought modem will deliver just that.....12 Mbps.
In other words, no modem or router can take the Internet connection speed that it receives and make the signal go faster.
Your local network behind your router can handle much higher speeds than ATT can ever hope to provide, so think of your local network as if it were a fire hose and the ATT connection as if it were a garden hose. You can connect a garden hose to a fire hose with the right adapter, but you will never get any more water out of the fire hose than the garden hose can deliver.