To be honest, I find this whole business of signature gutiars and stuff a bit strange. Yes, I'd love an affordable Squier with MK specs, but we'll never get it.
Why an artist would want a signature instrument? If the goal is to inspire people to play guitar, then an affordable version would be of great help. I never understood why someone, if he's an accomplished player, would want to buy an expensive professional instrument built with someone else's specs in mind, it doesn't make any sense. If anything, the player who can justify buying a professional instrument might as well make a signature guitar for himself. Hell, even myself, I have a guitar that I'd make my signature instrument — Squier Mini Strat, I'm just obsessed with the little thing, I love it so much and take it everywhere.
And now, oh my god, we have a signature toy replica of a signature guitar, it blows my mind on so many levels. But whatever, people will buy it anyway as jbaent said.