BYU and ND could get invites, but ND will not join a conference unless it is forced to join a conference, like if the four 16-team super conferences are formed.
Money is not an option for ND, otherwise they would have joined the Big Ten. ND values being an indenpendent not joinging a crappy conference and keeping its TV deal. ND has a TV deal now with out a conference, thus they will not join any conference unless their status within the BCS is compromised by some sort of major reallignment scenario playing out.