Some people do, but I don't think Nintendo Power would... professional magazines and media sources almost always list it under Adventure or Action Adventure.

Okay, so here is what I think.  First of all, I completely disagree that this has to be an old franchise.  I also completely disagree that this in any way must be related to memory loss.  That's stretching things a lot.  That said, old franchises are not excluded either.  So, with that in mind, these are the most likely candidates:

Nintendo in-house RPG:  This has been mentioned a lot, but Nintendo clearly bought Monolith so that they'd have an in-house RPG maker.  If you don't think that Monolith will be making a Wii exclusive RPG this generation, your are simply insane.  There will be one.  Whether this is it or not remains to be seen.  This RPG could also use other studios such as Retro.  (This would be cool. 

Suikoden VI:  This rumor has been tossed around a lot recently, and it does seem likely given the sales of the Suikoden series.  However, would Suikoden really be big enough to warrant such a statement?  I don't think it would.  It's got a cult following, but it's not even mainstream among RPG fans.  (Unlikely, if it's going to give all RPG fans an orgasm)

Baten Kaitos 3:  This also may happen at some point, but I don't think this is that point.  Like Suikoden, the games have a cult following, but are not mainstream among RPG fans.   Still, I'd say this is more likely than Suikoden simply because this is Nintendo Power and they have always championed the series. (Possibility)

Skies of Arcadia 2: This is another of those games like Suikoden and Baten Kaitos that may very well happen, but most likely wouldn't warrant this sort of attention.  Still, it's an option, and I could see Nintendo Power getting really excited over the option.(Never played it so can't comment)

A Final Fantasy Remake:  A lot of people have suggested this (FFVI or FFVII).  As big as those games would be, neither would be particularly secretive.  Perhaps FFVII, but I really just can't see Square doing that.  I would love an FFVI remake, but that will most likely be on the DS, not the Wii, and the way they were talking about this it seems to be for a Wii game.  There is only 1 DS game I could see them getting this excited for, and that's...(If it was VII, that'd be a nice kick to the groin for Sony fans XD )

Super Mario RPG 2: Apparently everyone already forgot this rumor, but back in November, GoNintendo had posted rumors of a bunch of RPGs comming to Nintendo systems.  These were from RPG Magazine.  Among these was Super Mario RPG 2 for the DS.  THis would certainly warrant every comment made by Nintendo Power, and it would be a huge announcement.  Very likely IMO. (I know what you mean by Super Mario RPG 2, but it's not like they've been stingy with 'Mario RPGs'.  There was one on the N64, 'Cube, GBA, DS, and Wii already)

Golden Sun Wii: Certainly a popular series on the GBA, this would warrant some major attention.  The rumor has also been very persistent, and IGN mentioned that they were 99% certain it was going to happen at some point.   I'm not sure how "secretive" this would be, but it could be a big game.  This was among the RPG Magazine rumors

Ogre Battle Wii: Along with Golden Sun and Super Mario RPG this was the other RPG Magazine rumor.  This would be pretty big to a lot of people (myself included), but probably not big enough to warrant the comments made by Nintendo Power.  Honestly, I would love for this to hapen.  Pretty much more than anything else.  It's a possibility at least.  

Kingdom Hearts 3: I figured this was worth mentioning, but it's really not very likely at all.  Nomura said he wasn't even going to start KH3 until Versus XIII was done.  (This doesn't mean anything.  Before Halo 3 was announced, Bungie assured us that it was absolutely not in development, and that they were working on something else.  Sound familiar?)   Plus, Square wouldn't want to steal the hype from their spinoffs comming out this year.  I don't think this is it.  It would be big though.  (I don't think it would steal hype, personally.  KH2 was announced after CoM and didn't steal any of its' hype)

Mother 3: Just mentioning this because twesterm listed it as one he wanted, but I'll say it's not going to happen.  Mother 3 is already out in Japan on the GBA, and Nintendo has repeatedly refused to localize it.  If it makes you feel any better, the fan translation is almost done.  

Final Fantasy XIII Spinoff (or other original FF): This will happen eventually, but would Nintendo Power get that excited over a spinoff of the series?  I actually think they would.  It's certainly a possibility.  Especially on the tail of Square's recent comments about how the DS Wii and PS3 were their main development platforms.  (I really don't think that Nintendo would accept a simple spinoff of FFXIII--since it's a spinoff of their opponent's biggest game, it would further the idea that they only get the leftovers.  A non-numbered sequel would be cool, though.)

That's basically my summary of the situation, and the likely games.  If there is anything you guys think I should add, let me know. ^_^