I doubt it. Leylandii take a great deal of nourishment from the soil and I think that for a new laurel hedge to thrive you would definitely need to have some of the old earth carted away and fresh soil put down, as well as digging in some compost and fertiliser. Incidentally once laurel gets established, it will grow very quickly and you'll find yourself with the same dilemma as you had with the Leylandii in terms of having to cut them back regularly.