I'm pretty sure that there have already been a few practical applications that provide some degree of invisibility using a few completely different approaches. It doesn't have to be perfect to still be very useful. Some of the "DAZZLE" camouflage experiments with airplanes during WWII showed that useful levels of invisibility could be attained in relatively simple, low tech ways.
I'm confident that at least to a certain extent, it's here now. I wouldn't assume that it doesn't exist just because we haven't heard much about it. Those who want it badly enough to spend the necessary amount in R&D probably will find a greater return on their investment if they keep it quiet.