I see something along the lines of a group abusing the release of alchemy being a main part of the story potentially giving Alex a chance to be a recurring character. Other than that I only see the chance for them to explain Isaac's situation.

If anything happens with Mt. Aleph I'd expect it to be the stage for a final battle rather than a place left to be guarded really. After all Vale should have rebuilt the village there already anyways so I bet there's a pretty good chance that guarding isn't much of an issue here.

I imagine that the story will go something like this:

Alex revives.
Kidnaps Issac or if set further in the future, kidnaps Issac's descendants in order to get the remainder of the Golden Sun's power.
Main Character's family member is kidnapped, probably little sister if not Issac as father/grandfather. main Character goes on quest to get her/him back, is joined by other people with other quest needs. Main character has some kind of divine Wise-one protection against Alex.
Visits lots of places chasing Alex, see how Weyard has changed.
Alex somehow gets GS.
Bad stuff ensues.
Party has to go to other places to gain the ability to seal Alex's power, including Anemos and over Gaia Falls.
Party fights Giant Dragon thing, seals Alex.
Main Character's family is saved/brought back to life.
The End.

I'd also say there is a 50/50 chance that some kind of light/dark world mechanic, or some kind of time travel mechanic will be implemented in the game.

bbb's got the right of it, I think. Other party members will likely have ties to characters from other games.

Surprise ending: the world explodes. Just once, I'd like to see it happen...

I sincerely hope that a light/dark world is not implemented when Camelot could do so many other less over-used devices instead. A new continent(s) beyond/at the bottom of Gaia Falls, floating network of cities made by the Anemos, etc.
Time travel might be neat, though. Just depends.

I don't think any information on whether Weyard has changed or not has been released as of yet. Hopefully sometime in the spring we'll get a nice press release to disect.

I bet there will be some changes to it so that Weyard has a new feel to it but also giving the feeling of it being a familiar place you've been to before as well. After all that would be a nice way to reward long time fans.

hmm.... golden sun ds is gonna be one of those games where everybody is gonna hype it up (including myself). its gonna either be a very awesome (which i hope and believe) or its gonna fall wonderfully short (which i have a bad feeling about) and despite its possible suckage people are gonaa think its awesome.

As for plot details its gonna follow Isaac's son (unconfirmed, but come on, just look at him!). So its entirely possible it will solve the now age old question of who Isaac does the dirty with (i personally prefer Jenna but whatev), i can just imagine the fanart and fanfiction that gonna come from finding out who. so if anything we prob get to know that. and other pairings. wait... does anybody remember Susa and Kushinada saying that their son/daughter will willingly come help them in the future. meh, i can only imagine the possibilities of just pairings and the childrens effect on the story (you know like you only see three in the poster and there has to be more, right. the eight heroes, Feizhi, Eoleo, the three from Izumo, proxians, lemurians, the baby from contigo, the colosso guys said they were gonna train in the same warriors skills as Isaac. thats all i can think of off the top of my head.

alchemy was released so its entirely possible that like feizhi, people can gain the ability use psynergy even if the trait is inherently there, though technically they could before using psynergy stones. people could be experimenting with it and technology. they could actually pull a thing like final fantasy 12 and have fantastic machines powered by psynergy or the stones, yet at the same time they still use swords and the like.

war could be widespread like a war between the different types (venus, mars, jupiter, mercury) towns become cities maybe countries like citystates. etc.

man im talking a lot i cant stop this from pouring out.

Alex has 3/4 of the power of alchemy. whatever that means??? anyone actually understand what that entails. and Isaac has the mars star and/or its power meaning he has the other 1/4 of it. So i can imagine an epic battle where Isaac and Alex face off, with the very sad possibility that he will die and thus before he leaves he gives his son the power and its a story driven by revenge? meh i just dont know.

plus theirs the possibility of people who are naturally adept at more than one element or someone who is like the avatar and is good with everything. its all merely conjecture.

maybe the old heroes will be bosses for whatever reason. or maybe some will die, again for whatever reason (Alex going on a rampage and because they are caught by surprise or they are protecting the new main characters or they are outmatched.)

whatever the story is i hope camelot realizes that the fans of this series, while they may have been as young as 10 or twelve when they played it are now adults or almost adults and while doesn't have to be an adult game they dont have to hold back quite as much in terms of dialogue and story. for instance have an actual romance not just hints. i mean for a game and not only that a GBA game the golden sun series has a huge standing and fanbase that like to write about the romances that are hinted at. if you have a romance between main characters it'll give fans something to talk about instead of just guessing who is with who. i digress i just hope its a little more mature and its good enough not to live up to the name but exceeed it.

sigh that was alot if you read it all, thanks.