Well, I really doubt Nintendo will ever really release the rest of the Mother series northside. Now, in Mother's case, a North American release is a little more likely because they fully translated it before deciding not to release it after all -- the NES was more or less dead by this point. However, if they still have their hands on a copy of the original translation (I doubt that the beta cartridge that made it out to the public and then into ROMland was the only one they had,) they're certainly capable of dumping it to ROM or whatever it is they do to turn old games into Virtual Console pieces.
Now, Mother 3 is another matter, I'm afraid. Looking at the labours of the people over at the Mother 3 Translation Project, it's clear that the game was never coded with a North American release in mind. The team has had to go right into the game's guts and jigger a lot of subroutines, and they've been working at it for about a year and a half now.
That said, Nintendo of America, unlike Mato and crew, have access to Mother 3's source code (which would really be instrumental fixing most of the game's hesitations regarding English, since all Mato and crew have had to work with is the compiled code itself,) and could probably get twenty times the programmers working on it as Mato, jeffman, byu, and everyone else have.
Of course, there's another issue. I'm afraid of Nintendo censorship. People continually assure me that Nintendo's censorship isn't "that bad anymore." I was sort of freaked out when they took the Red Cross off of everything in Earthbound and all that, but... I certainly hope they realize that Mother 3 isn't just a kid's game if they ever decide to localize it. Mother 3 is laced with death and sadness. It's part of what makes the game's atmosphere so unique -- it's wacky and offbeat at times, like the other two instalments, but it has some very emotional bits as well, and the two faces of the game are able to coexist without any sort of audible shifting in gears. I'm not so worried about the little visual gags and light instances of homoerotic humour, because they're not such big contributors to the game as all the tragedy is. I'm just afraid that Nintendo would try to make the game "kid-friendly" by removing or softening most instances of death in the game -- that simply wouldn't do! (After all, the Red Chimera wouldn't be half as badass if it didn't kill helf the people in the Facility before you first see it.)
But yeah, Earthbound was the number one game on their list, and I think they're going to make good on that commitment. After all, Sonic was the number one requested third party character (another day, Geno, another day,) and he was placed in Brawl, after all. As for the rest of the series, well, Reggie and company have been ignoring the great pains that tens (hundreds?) of thousands of Earthbound fans have taken to date (and these are all people who would be guaranteed to buy Mother/3 if it came out, too, let alone all the people new to the series who would be interested if they didn't mess up their advertising again.) But, I dunno, now that people have voted Earthbound the number one Nintendo console game of all time (in essence,) maybe they'll start to shift their paradigm a little.
Let's just hope. : D