Like someone else said... I'm sad that Luigi's Mansion got pushed, but getting firm dates for Paper Mario and Professor Layton went pretty far in making up for it.
Anyway, I'd guess that Luigi's Mansion won't mean much of anything to Fire Emblem's release. Honestly, Fire Emblem is a pretty niche series, so there's no reason to avoid releasing anything else around it. Unless they have a huge marketing push planned, of course, but I'd wager that's not the case.