They're definitely doing their best to bring in a large western market by featuring such well known actors in Kingsglaive.
This is such a bizarre move though, and one I cannot see capturing Western audiences. Yes, there are some big names in Kingsglaive, but I can't see anyone who is a fan of Aaron Paul or Lena Heady even
hearing about Kingsglaive, let alone saying to themselves "Oh Jesse Pinkman is in a CGI movie about a JRPG that I barely know about / a series I haven't played. I definitely need to watch that." It's such a strange detail.
Square actually tried something very similar with the Kingdom Hearts series: casting big name VAs for the English dub (Christopher Lee, Billy Zane, many of the original Disney cast like James Woods (though that's a very Disney thing), Sean Astin (remember that LotR was big at the time), Mandy Moore, David Boreanz, and so on). The series's success in the West of course is due in huge part to the inclusion of Disney characters and franchises, but I think Square quickly learned that nobody in the West said "I'm going to play this weird game because the guy from Titanic is in it." They're still casting big names in the games, of course, like Leonard Nimoy and Mark Hamill in Birth by Sleep (though Mark Hamill is such a prolific VA that I don't find that too surprising), but whenever a friend asks me about the series they're surprised to learn about some of the VO names involved. So while the trend is continuing in recent years, the number of celebrities doing voice work in the series has seriously dropped off since the first game, for whatever reason.
My point being, names recognizable to Western audiences aren't enough to draw the casual audience into a very niche thing (Japanese and anime-styled CGI movie for adults about a video game). And further, given the objective quality of Square's previous movie ventures, even the few drawn into Kingsglaive by the voice talent probably won't be too impressed by it.
The success of FFXV hinges on its capturing Western audiences and while the game has made some serious concessions from the series's routes, I too have doubts that it will appeal to the same people who embrace things like Skyrim, Assassin's Creed, The Witcher, Call of Duty, etc. Good on the dev team for being ambitious and believing in their product, but the 10 million units goal is frankly laughable. To my knowledge the only game in the series to perform that well was FFVII, but that was in a very different climate for the video game industry.