"You can download video on wifi before you go where you're going..."
I would argue that the advantage of having fast wireless internet is that you do not need to download anything over WiFi at all. Of course there is a volume/cost factor - but more and more mobile plans now include very high or unlimited data, to an extent that WiFi isn't needed any more even for high-volume requirements. So it's all about speed.
And for speed, with existing 4G you have theoretical 300Mbps peak, and good 4G signal is consistently 60Mbps. UHD video stream is taking about 25Mbps. On a screen the size of a phone, you can barely tell the difference between HD and UHD, and for tablet screen size, you can't get resolution higher than UHD anyway.
I'm struggling to come up with any requirements in the next 3-5 years that NEED 2Gbs+ that won't work appreciably as well with 4G speeds. Of course, there's that Bill Gates quote about memory that comes to mind, famous last words and all that...