when usb is not enough?

the question that has bugged me for the longest, what will we do when USB is no longer enough to charge
our smartphones? everyday these phones get smarter and faster and as a result, they need bigger, heavier duty batteries. obviously there's a limit to what 5v @ 750mA can provide. already my droid razr uses a 3 amp battery, takes me hours to charge and it's going to get worse. so what is the solution?
of course there is a higher voltage barrel plug, like on some tablets, but how inconvenient is that? you need a whole new
power supply that only works on an AC outlet. and forget charging and syncing.
does anybody have a suggestion?