Unfortunately the big names like Nintendoh would not give the roms away for $2. That would set a precedent which would interrupt their revenue stream. Besides that $2 rom is worth more every year. We see home console spin offs, anniversary editions, and the XBLive reboots are just a drop in the ocean. Sega is another entity that would suffer from a $2 rom sale. Folks like Atari who have been sold off to every tom, dick and harry might lend a trademark or two for licensing but even their game roms are owned by Hasbro. Something along the lines of "only over my cold twitching corpse before I sell my IP for $2 a pop" which seems to be a very smart move.
It will not make the business leaders happy, but it will generate new revenue, because they do not sell or license the original games in their original forms, at all, anymore. It will take some willing licensor to make the leap in order to prove that I am right or wrong.
It will all be income; there is very little infrastructure required to release ROMs, and there will likely be DRM surrounding the ROM, but if that enables me to play an arcade game, legitimately, which I do not own the board for, then I will accept that with open arms.
Wait until we migrate to the new Orwellian system where M$ and Apple start cataloging our HDD contents and reporting IP violations to the owners. It will make patent trolling a game of the past and turn it into IP trolling. It will happen, so I would be keeping your cabinet off line from now on if I was you.
To which new Orwellian system are you referring? I am surrounded by them in my daily life, so you'll need to be more specific. Also, there will always be Linux, which I recommend you gain experience with if you've not already. That includes all readers afraid of Orwellian stuff.
The decline of the arcades?
I do not think so. Arcades are not dead. Just because you do not see a cabinet in every liquor store, laundromat or Pizza Hutt.
You just need to whip out your Galaxy Note and fire up a few games. You just have to buy the $2 apps from Namco.... 
There has been a most definite decline in arcades. There is zero argument on this point. We, as arcade hobbyists, do not see it because we surround ourselves with other people who talk arcades and play arcades and build arcades and restore arcades, continually. Drive to a small town. Any one, pick one. That town used to have an arcade, if it has 2k residents or more. Where is that arcade now? Drive to the next town, and the next, and the next. When I was a kid, every single town large enough to have its own school district had an arcade. Every last one. Now, it is hard to find a proper arcade in a town smaller than 50k residents. I work in an urban region with 400,000 people in residency and there is 1 arcade with 67 machines, and that's it. There were over 40 arcades of that size in this area 30 years ago.
The arcade business has most definitely declined. We are not as apt to see it, though, as we blanket ourselves in arcade stuff constantly.