In the second movie, Marty makes a trip 30 years into his future, to the year 2015, where he encounters hoverboards, flying cars, holographic 3D movie advertisements, jackets that adjust themselves to the wearer's size and the aforementioned Nike Mag. Unlike the 1985 version worn by Fox, people who buy the 2011 model will not have to have battery packs in their clothes with wires running down to the lighted portion of the shoe. They also don't lace themselves as do the shoes n the movie.
It's nice of Nike to make a substantive gesture like this for Fox's foundation, but there is no getting around the fact that the shoes are just plain ugly -- it's hard to imagine people actually wearing them. They don't look particularly comfortable, either.
One interesting note is that the replica Mags have the Nike name on them -- which few Nike shoes other than deliberately retro styles have had for several years. Most of the company's shoe offerings these days just feature the iconic swoosh without the word "Nike." But movie designers in 1985 didn't foresee that, so when they made their 2015 shoe, it had the word on the back heel and on the strap.
All this means that scientists have got just about three years to get us hoverboards and flying cars. Someone had better get cracking.