The style of music definitely has some mainstream potential like Mastodon has received. I can't wait until their next album as it should be a big one for them (in terms of sales or more exposure). I remember hearing some of Leviathan when it came out years back and I didn't like it. I didn't give the band any real attention again until this year, and they are now among my favorite modern metal bands. I've got Crack the Skye, Blood Mountain, and even Leviathan. It's definitely worth checking out bands after a few years in between listens since you never know when your tastes change.