The multiple SKU thing didn't work for Sony when the PS3 launched, and there's zero evidence or rationale to believe Sony will try that again with the PS5 - especially when you consider that the single SKU selling statistics for the PS2 & PS4 were VERY strong.
Oh and the PS5 won't be $500, that's equally stupid to assume as well. Because like the multiple SKU tactic - they tried a high price point and that failed too. There's a high probability it'll be $450.
A $350 PS4 Pro/$250 PS4 price cut announcement is gonna happen in several weeks for North America and EU territories. (The Pro is already $350 in Japan)