You are also forgetting that, for the most part, 80's/early 90's emulation is mostly finished.
Even if the VGIAA (Video Game Industry Ass. of America fictional) cracked down, threw every mame dev in prison (heaven forbid), you, and millions of others, still have a copy of Mame. They can't throw Bob Roberts, or Happ, or Saint in prison. Just building a cab isn't illegal. This hobby won't die to VGIAA.
Mame could stop tommorrow, and I would still be satisified for decades.....