The reason I asked is because I ALREADY have a hotspot and dual antennas. So I wanted to know if I could use Visible with it. It sounds like the answer is no, so I won't sign up for Visible.
Also, there are huge technical advantages to a real hotspot over a booster. The way 4G works really favors dual antennas, because your device is able to look at the signal from both antennas as a pair, and improve the speed that way. Also, on the broadcast side, your device will broadcast with both antennas. A booster breaks all of that. It only receives a single signal, and when you send data back upstream, it basically receives the signal that the phone is broadcasting and broadcasts it again, in addition to the phone's own signal. This can actually hurt the upstream speed.
In short, boosters help range, but can actually hurt speed if you are already in range. Whereas a real hotspot with a good pair of antennas helps both range and speed.
As far as futureproofing, neither a booster or a hotspot will continue to work when the standard goes from 4G to 5G. Antennas might still be good though.