I did bring it up briefly at
the Newcomer/DLC discussion thread as a food for thought but I wasn't sure if it was something worth looking too deeply into as the whole thing is a bit finicky with no one being entirely sure which characters were based on who outside of theories and rumours. (Though then again, I suppose that's what speculation is all about)
It would be nice if it did lead to something though, I suppose I could see them using Ness as a base for Layton due to both having eyes that are mainly just a simple texture (So no need for rotations of pupils/eyeballs etc) and one of the gadgets working off PK thunder to speed up dev time.
I'd imagine Layton would probably also be modelled by the same guy that modelled characters like Ness and Lucas due to their more simplistic looking design's.