Would it be exclusive? If yes, I believe that is a large pro.
Still, remakes don't sell that much. FFXIII on Ps3 is going to sell what? 3 million? 4 million? That's a lot.
A FF7 remake would probably be large (ala 1.5-2M), but it simply cannot match a completely new game, no matter how much advertisement and such it would get.
As a general note, remakes don't outsell new installments. That (almost) never happens. If it happened with Final Fantasy, there would be something seriously wrong happening to the series.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS