The problem with these sorts of hoaxes is that they tend to get taken seriously by the people they're supposedly satirizing.
Using the OK gesture as a "white power" sign started as yet another 4Chan hoax; but was very quickly picked up by various neo-Nazi and other white nationalist groups, who didn't quite realize they were being trolled.
Now, a slight variation of the gesture is being used, in all seriousness, as a white power sign by white nationalists. What started as a hoax very quickly became reality.
I doubt anything similar will happen for the hash sign, given how ubiquitous and necessary it is in many different contexts. This one is likely to stay nothing more than a joke.