I don't think lowering the skill level is something we will need to worry about as over time this actually trickles up, A Creative professional trained with AI tools will almost always top a Amateur using the same tools.

The real issue is Style. If you are an Artist with a very recognizable specific style, and you make your money trough commissions you are basically screwed. Many Artists feature a personal style and while borrowing peoples style is common (disney-esque) it's usually not a problem because within a unique and diverse human mind it rarely results in unintentional latent copying.