Yes, but on the other hand, in Dragonball's era it stood alone, too. I mean, Toriyama is considered the Number 2 Manga Artist of All Time or something, and that's only second to Tezuka. And he made, what, two series. And that was it. And yet he entirely recast shounen--completely rebuilt it.
I believe that Attack on Titan is an act of genius, but I don't think that even it stands up to Dragonball. It's amazing, but it isn't... well, the author isn't strong enough yet, that's all. He makes some rookie mistakes. Probably his next manga, if he manages to go full-speed ahead for that one and take a weekly.
The thing is that I don't think shounen is dying at all. I think it needed a chance to catch its breath after someone like Toriyama rolled through and fucking flattened all the other authors, set the standard, etc. So it took a break while the world enjoyed its moe-moe harem shows and adventurey sci-fi/fantasy stuff, and now it's starting to actually absorb the demands for interesting female characters and so on (that's what started running Naruto into the ground, popularity-wise--an extremely vocal female fanbase in Japan let Kishimoto know that they felt they had been repeatedly betrayed). Bakuman was a direct and performative commentary on what New Shounen needs to look like, and now Attack on Titan is taking those lessons fully to heart and running with them. That's why I'm saying I think Attack on Titan will usher in a new era. It has great representation, a large cast, no special costumes or transformation sequences, doesn't operate on honor, keeps a hold on its tone, has excellent arc design, and most of all it doesn't over-explain itself--but it is still about the shounen fundamentals of trust, friendship, loyalty, and living well under sincere duress.
And the thing is, I think that this is the manga that will make Dragonball look completely hokey and outdated. It's just this feeling--all the good manga have been going in this direction recently. I think this is the watershed. And I think that, after this, we might just get another piece from this author that will epitomize the pinnacle of this particular direction, and that will be that.