Downloading songs isn't illegal, if you pay for them and download them through a service like iTunes then it is okay but if you get it through a torrent or Limewire or something like that without paying for it, then yeah that's illegal.
if they discontinue it, theres always going to be another P2P software thats going to be produced, and people will just find another way to get their things.
It costs too much time and money to do something to a program like this.
America's economy is already bad as it is.