It's almost certainly going to be an XBLA release anyway: -
PEGI outs Dragon's Lair for XBLA | VG247A rating for an Xbox 360 version of Dragons Lair has just appeared on the official PEGI website. The rating, a PEGI 7 with a violence warning, was awarded on the 16th.
The rating lists the publisher as Microsoft Ireland Research who are also listed alongside the ratings of games including Alan Wakes American Nightmare, Trials Evolution, Ms. Splosion Man and Retro City Rampage suggesting this is an XBLA release and not a disc.