Music as a service would be called concert venues. Basically, the bands would distribute their music in a recorded form as a way of advertisement over the net, and use it as a way to try to attract people to attend their live performances. They could then also attempt to sell other merchandise options, including CDs, if they still have value to their particular audience. Many smaller groups have had decent success this route, and it also gets rid of the need for middlemen like the RIAA. What we are seeing today is the music industry trying to fight tooth and nail to not be made irrelevant, even though they don't really add much value, if any, anymore. This sort of a model works, and there's many indie artists who have proven so. So in short, I'd say that there's plenty of people that would support that.
As for software as a service, the way you describe doing it is not software as a service, persay. I'd describe software as a service being done successfully as utilizing parts or all of a few different models. The first is cloud type services, like MMORPGs, or other online apps. These make it irrelevant as to whether you own the software or not, since what is really being sold is a subscription service (much like rentals). The other model, which I haven't seen a lot outside of the business world (which is a shame, really), is ticket based release. This is a lot like setting a bounty up on different targets, then being able to cash in on those bounties when those targets are acheived. So, developers can place down target features on a site, and let users invest in what they want to see done. Then, the company is more likely to chase after tickets which have higher bounties on them. The last way that I can think of that can be rather successful would be to sell support contracts. This is a lot like the last suggestion, but which is instead a flat fee paid monthly, yearly, etc. in which you're guaranteed that if you happen to have a problem with the software, that you will be able to have someone be able to resolve your issue, and will work to make custom patches especially for you if needed (or for your own software running on theirs, if needed).
Is it as much of a cash cow as the current way of doing things? Well, it depends. What these sort of models force you to do is to think smarter, not harder, which scares a lot of people. However, I think that it's inevitable that we will eventually arrive at a point where this will be the way in which media is handled. You can only keep fake barriers going for so long before you're just hurting yourselves by doing so (for instance, living off of a lie). I think that industries which are trying to uphold the old way of doing things are eventually going to either die off like the buggy whip makers or embrace and utilize alternative revenue streams that don't rely on them inflating an artificial market. We've seen this time and again throughout history, and we've always killed off leech or dead industries. The arguments that we see now were said about just about every technological advance that has ever been made. The difference is that now we seem to be paying them far more attention than they have gotten before.
In any case, if any industry really cares about adding value for their products, all they really need to do is to continue to do things for consumers that they can't do for themselves. If they fail to do this, then they should rightfully die off. If copying is at a point where any consumer can do so with ease (and it is), the answer is not to cut into your own profits by trying to kill that, the real answer is to change your business model to be able to acknowledge that your copying is no longer providing any value to the consumer. The sooner businesses realize this, and stop treating consumers as guilty until proven innocent, the healthier of a marketplace we can have.
