In case u didn't know, it is just a soundtrack for the promotion of Kylie's products, not even a release for his own collection.
He might become 'mainstream' because a lot of people are noticing him lately. Sicko Mode might be 'mainstream'. But if you say that Astroworld is a mainstream album then I just pity you. The guy is always creating new experiences and different kinds of music with his album(s). This makes him also avoiding making the same kinda shit over and over again like most of the artists in the rap/music game
I promise u, he'll never let u down with his albums