All horses can go barefoot, if the right holistic management is attended to. No horse NEEDS shoes.
HOWEVER, I don't disagree with much of what has been written above. It depends on a lot of factors - quality & frequency of trim, diet, environment, conditioning, to name a few - as to whether a horse can develop tough go anywhere, do anything feet. Most horses are managed in a less than ideal manner in this regard and so they generally need some protection on some surfaces.
Hoof boots are fantastic for this purpose, providing true protection that a rim of steel can't. Some horses & work requirements are inappropriate for hoof boots tho, and in that case, metal shoes may be the best option.
There is a big difference between a "B"arefoot trim and a basic what I call, pasture trim. Most farriers will trim a hoof as if they are going to put a shoe on it, then just leave the shoe off and call it a barefoot trim. If you want to go barefoot either hunt for a good farrier who either knows how to do it or is willing to learn. I've got the Pete Ramey and Jaime Jackson books that I tried to give to several past farriers to even look at the photos and trim my horses this way....None were interested. Thanks goodness we finally found a great barefoot trimmer. 
