It wouldn't be weird if it was an international release. Honestly, SE has plenty of time to announce a release, so Gamescon really isn't their "last chance". I'm also not sure about a Spring release as while it's favored for the Japan because it falls close to a few Japanese Holidays like Golden Week, the sales there are not what they used to be as console/handheld title sales have been falling for the last few years. They could easily target this for a Western release which would make Fall a better choice or even Holiday season if they wanted to, it's not like numbered entries have ever had issues with sales regardless of when they were released so competing with heavy hitters like Madden or CoD wouldn't really be an issue especially since all three games most likely target very different demographics of gamers. So honestly it could be even be announced for a Winter 2015 release by this logic.

Traditionally, any entry that has ever had a demo is usually released within a year of the demo's release. I'm betting it will be released next year, but at this point the game's development doesn't really affect KHIII or the VII Remake as both titles are being developed by different teams so it's release should not affect them unless the game tanks but even then XIV will cover the cost (never thought I would say that...) so I wouldn't worry about it either way.