It'll be a long time before it threatens fiat if ever unfortunately. People are just too stupid.
Very few governments care about folks buying smoke or working for cash so long as its small scale, its victimless and it costs too much to chase down so they just aren't interested.
They care because they want their cut of the profits and that's what will happen to bitcoin.
1NpxFwWyWi9gdibJXDkYDFk9krtyiQZuq1