Here's my two cents on the matter.
Firstly, as stated before, why did Opeth choose Road Runner? I'm sure RR wasn't the only record label seeking to sign Opeth, and I'm sure there were more suitable labels providing offers.
Secondly, this pertaining to my first thought, no I don't think that Opeth signing to RR is selling out. It seems that some of you have some sort of preconcieved notion that because some one doesn't like that Opeth has signed to RR that, that person thinks Opeth is going to sell out, or is going to change their sound, or just some other nonsense like that.
Thirdly some of you sound like you just got back from sunday school. With "lets convert all the nu-metal kids into Opeth fans, it will be good for them to like good music!" First of all who's to say what's good music? Then I hope it just makes you sleep so much better at night that somehow you're bettering the world by doing such acts. Maybe I should come knock at your door and ask you if you'd like to find salvation. On top of that, what's with the whole "Mikael said they're never going to sell out, so they're not."? Yeah I know some of you people really do think Mikael is Jesus, and everything he says is true. Are you that blind that just because he says it, that you won't think that perhaps it could be untrue? Once again I'm not saying Opeth is going to sell out, just saying that perhaps people shouldn't wear their blinders all the time. And with my final allusion to Christianity here for you sheep...Here's something that perhaps should be taken into consideration; moderation.
I firmly believe there needs to be an equillibrium in music. This regards anything from exposure, to fans, to whatever regarding a band or genre of music. I think music thrives the most at a stage where Opeth was probably about 3 years ago. Here's why I think so.
Over saturation.
I think most people would agree that most popular music is diluted and contrived. Atleast that seems to be the general consesus when people refer to such musical genres as nu-metal, or pop punk, etc.
For an example, and only for that sole purpose I'm going to start with hair metal here. At the current moment most people laugh at hair metal. They think it's ridiculous. It was once popular though, and you could make a lot of money off of it.
After that grunge became popular. Now no one cares too much about it, besides people that somehow think Kurt Cobain was a musical genius, before however, you could make plenty of money off of it because it was popular.
Soon after there was nu-metal. It was popular, and you could make a lot of money off of it. Now most "metalheads" think it's some of the most ridiculous music ever created.
With the current music scene it's really trendy to listen to metalcore. However I think the same fate will fall upon it as well. Girl's pants and shaggy hair cuts will be replaced by something else, just like dyed hair and parachute pants were given the old heave ho in favor of the aforementioned. It could be another 3, maybe 5 years before this happens, maybe longer, maybe shorter, but it will happen.
Are bands such as Opeth the next in line? A lot of you measure success by money, or by how popular a band is, but here's something to think about...
"Success is to be measured not so much by the position that one has reached in life, as by the obstacles which he has overcome." Booker T. Washington
Now if all your wishes come true, and everyone listens to Opeth, and they're eating caviar for dinner every night, how long will it last? How long will they be on the top 40? How long will it be COOL to listen to Opeth? 5 years? More or less? It won't last long. I guess then they'll just be washed up has-beens. I guess they'll just be the next era of ridiculous music that will be mocked. It will happen.
It's like Emmit Smith, or Jerry Rice. They should have stayed retired when they did, instead of trying to continue on. Now they're just criticized for continuing. By this I mean you get to a certain point, but perhaps it's too much.
But back to over saturation. If a band like Opeth gets popular, you can count on others trying to emulate their sound, and if that sound is popular, and it will sell, there will be a lot of bands like them. But since we live in a commercial world and Opeth will be more like a paper plate than a band with a rich and long lasting legacy, of course at some point it won't be cool to listen to them anymore. They'll be used by the labels to make money, then thrown away like that paper plate, because convenience, and making more money is more important. On one paper plate you had nu-metal, another hair metal, and they were all thrown away for something else.
If it doesn't get to that point, and they ride that line in the middle. They'll have great careers, and be known as a great band. Rather than I remember that crappy band back from so and so.
On the other hand if there isn't enough exposure, than of course the music won't continue, but a band like Opeth is well passed that stage.