Firewire was not a flop and if Thunderbold does as well as Firewire is then I'll be a very happy Mac user for the forseeable future. Thanks to Firewire, Macs have been able to do things PC users could only dream of.
Thanks to FW the original iPod loaded music at least 10 times as fast as USB1, and was able to charge the battery in no-time.
Thanks to FW external harddrives have been constantly at least twice as fast as their contemporary USB counterparts, until the adoptation of extrnal SSDs attached to USB3.
Thanks to FW there's been bus powered external harddrives, many many years before USB could handle that.
Thanks to FW we could hook up digital videocameras years before those with USB.
Thanks to low latency FW with priority traffic FW enabled audio and video hardware that could never be attached to anything USB.
Thanks to FW we could daisy chain external units like harddrives, CD/DVD-burners, videocameras and a whole world of audio and video gear that USB users to this day can only dream of.
Thanks to FW we can target boot our Macs. That's something that USB will never be able to do.
Thanks to FW we could have our peripherals in another room, supporting cable lenghts of 100s of feet far beyond the range of USB.
Most of these features are replicated with Thunderbolt but not challenged by USB3 like much longer cable length, much higher bandwidth, lower latency, daisy chaining and target mode, and more electrical power. And Thunderbolt adds a lot of features to FireWire that's not supported by USB3, like monitor support, external PCIe expansion and protocol agnosticity.
Stuff we'll never see on USB are 4K (aka Retina) displays, 10 Gb Ethernet-ports (or multiple Gbit Eth) and bidirectional 10 Gb links is just the _first_ implementation of Thunderbolt. This technology is actually designed for 100 Gbps so it has room to grow.
So, no, it's just not designed to support the stuff like external harddrives so if that's your narrow scope of problems, USB is the solution.