By accessible you mean mainstream? Like it would be on the radio and it would be popular?
1. Is it possible? Yes. Likely? Probably not. (something new would probably be invented then that would be like the metal of today)
2. Societies morals completely change. But if it did I dont think there would be many "shallow" listeners.
3. Good thing? Depends. Benefits? Can go to any store and pick up what you want.
4.It may help, but I think that you either like metal or dislike it. It is somewhat of an acquired taste but overall I think that you will like it or hate it.
5. Pride (for what you like) isnt always an elitist tendency.
In short I dont think that metal (as we know it) will ever become mainstream for numerous reasons.
1. It is too brutal. We live in an age where you cant swear in public. Think of what would happen if someone turns on the TV and there is Vital Remains screaming "LET THE KILLING BEGIN!" or emperor is playing. Just thinking of what most parents would think...

(I dont think that how parents will think will change all that much either. Parents usually want what is best for their child, having them listen to songs about killing, evil, death etc isnt what most parents want.)
2. Metal is looked at as "satanic' and "evil" "will make you love Satan." There are to many religious nuts in the world who think like this. No matter what the truth is they will not listen. Now granted metal can be satanic, evil, etc not all of is. But most people will not acknowledge this.
3. Just in general how society looks at metal. Metal is for rejects. If you listen to metal you will kill people metal makes you commit suicide etc etc. If society becomes a bit (read a lot) more open minded metal may become more accepted, and move more into the mainstream. But I dont think it will ever replace a band such as green day or whatever the popular band is of today.
4. I dont think that most mainstream listeners can like metal. As I said before I think that most people will either like or hate metal. When you start to listen to metal it becomes almost a part of you. Most other types of music then become dull and repetitive and over all just dont appeal to you any more. This is not always true as a lot of metal listeners also listen to other stuff, but not usually the mainstream stuff. I wouldnt be surprised if a lot of metal heads also enjoy classical music.
*note I am making general statements, not everyone is like this. Just overall what I think.
No I dont think that metal will become mainstream. But should I be available to the masses? Yes it should be available to those who want it. As should all forms of media. People just have the right to choose what they want to see/hear/think.
If all that appeals to us about metal is that is underground (and fills a niche thing etc) then why dont we all enjoy the most underground black metal? Or even more underground something like polka (show me a polka scene and I will show you something underground (and a real special niche :Spin: ).
As for metals elitist tendencies. There are some elitist tendencies but I think that over all we just want metal to stay good. Who wants something they like to turn horrible and dull? We defend what is important to us. It can be easy to confuse elitist tendencies with pride. Pride isnt always bad.
Ehh I guess that is it. Sorry for the rant (you can blame having a 40 oz of coffee.