I can think of 1,000 "real use-cases" for cryptocurrency that are far more valuable than sending money to a country facing sanctions in violation of U.S. law.
I can probably think of more than 1,000. If you want cryptocurrency to "take off" I can assure you that using it to commit a crime will result in the opposite.
For cryptocurrency to take off, though, it needs real use-cases. This is as real as it gets.