Unlined fretless are not that common and the standard by big factories like Sire or even Fender seems to be lined fretless.
Being a fretless player myself, I've always struggled to find unlined fretless basses. That said, I ended up not focusing on this as I don't look at my neck that much while playing, only once in while.
So yes a fretless Sire P10 or V10 with an unlined fingerboard would be great, as long as they switch back to ebony, not doing this with a maple fingerboard, which is an heresy.
Hoping that Marcus Miller is a BassChatter and that the guys at Sire will read this thread too. And I think Nathan King is a BassChatter or at least someone at Andertons is.