This has the potential to sell well in the same way that 1970s Buick Regals had the potential to sell well- sure, it will probably be towards the top of Fiat's best-sellers list, but at that price and with the limited market of something with a Fiat badge, it'll never touch the numbers that it's Jeep brethren will have.
As much as Fiat will try to deny it, there are still people in the U.S. that remember the X1/9 and 131- those people might buy a Jeep, but I doubt if many of them would touch a Fiat with a 29.5 foot pole.