Does anyone know why Gen Con is so late next year?

I see this -

convention the week before Gen Con - August 7, 2017 to August 12, 2017 - Drum Corps International - DCI World Championships 2017

And this -

IndyFurCon 2017, Indiana's 8th annual furry convention, takes place Friday-Sunday, August 11-13, 2017 at the Indianapolis Marriott East

And I see this -

the last week of July - Sat Jul 22 - Sat Jul 29 2017 - Sat Jul 22 - Sat Jul 29 2017    United Pentecostal Church International North American Bible Quiz and Youth Congress 2017

But I don't see anything scheduled in the sweet spot between those 

Does anyone know?

GenCon 50's days were August 17-20 long before this (at least since 2011, I think).

The last couple years of early August are more the exception than the norm. Mid August is usually when it is.
2003: July 24-27
2004: Aug 19-22
2005: Aug 18-21
2006: Aug 17-20
2007: Aug 16-19
2008: Aug 14-17
2009: Aug 13-16
2010: Aug 5-8
2011: Aug 4-7
2012: Aug 16-19
2013: Aug 15-18
2014: Aug 14-17
2015: Jul 29 - Aug 2
2016: Aug 4-7

So while earlier is by no means unheard of, of the last 14 Gen Cons 9 of them have been in middle August, not early. If you go back to the Milwaukee years it does average a little earlier.
 

Yes, but the trend is for an earlier convention, which makes sense given the audience and the start of the school year.

2015: Jul 29 - Aug 2 
2016: Aug 4-7

Event                       Scheduled date
Gen Con Indy 2017   August 17–20, 2017
Gen Con Indy 2018   August 2–5, 2018
Gen Con Indy 2019   August 1–4, 2019
Gen Con Indy 2020   July 30 – August 2, 2020

Those couple of weeks are killers.  High-school and college students and staff can't attend.

And on a personal note, the middle of August is Ragweed season.  I'm always fighting what feels like a nasty cold that time of year.

 Every week is going to be bad for someone. The schedule is published years in advance. It is frustrating that schools open earlier and earlier each year, but that's not anything gencon can change, complain to your local school board. We can't all fit the entire summer into three weeks in june, which seems to be where we are headed. Just like sunday is still a day of gencon, august is still summer. Don't leave gencon sunday morning, and don't go back to school in early august.

 I for one will pull my kid out of school for summer activity without hesitation if they start school prematurely. I get it that they want to get in as much test prep as possible before standardized test dates, but education isn't about teaching kids to score well on standardized tests.

 And really don't go Christmas shopping during gencon. We have Christmas commercials on TV and radio, and it's September. Everything in it's time.

Here in Western KY (or my part of it) school starts the 1st week of August so anytime in August would be bad -- if I had kids or worked at the school.  So, yeah, there will always be people who can't attend because of start time of the con no matter when they have it...