Hopefully the chances are low. I like Lucas. He's a nice protagonist, but replacing Ness (who is the one and ONLY main hero of the Mother series that America has seen, or will ever see) with a character that Nintendo has pointedly decided not to send over to the states seems like it will overly alienate the western audience, especially people who grew up with EB but didn't necessarily know that it was actually a series of games.
I'm all for one of the Mother 3 support characters getting in (Kumatora, Claus, Boney/Bonnie and my personal favorite, Duster) and if they manage to find a way to include Lucas without cutting Ness out of the deal, I'm all for it, but if Ness goes, then I personally won't be able to enjoy the game as much as I would have if Ness was in it. Ness is that important to me.