Yesterday, I started typing that I wouldn't put the over/under over 7500 yards, based on discussions I have had with tour pros. Even in that limited segment of about 200 players, there will be two groups - those 30 that bomb it over 300 yards, and the rest who don't. If it is only top money winners, who tend to be long, it might be higher, like 7600. For shorter hitters, I speculated their consensus might be lower, but probably not under 7300.
Today, I received a surprise phone call from a three time major champion, famous for being not too long but really accurate. He mentioned in his peak years he hit 80% of fw and 70% of greens, according to the PGA Tour stats, adding many of todays long hitters might be half that (probably exaggerating a bit)
Briefly describing Tom's upcoming meeting, he pegged ideal Tour length for today's players at 7400. He said, "It depends" citing elevated tees as one factor. Surprisingly, he used Merion and Erin Hills as examples, nearly word for word from some posts here, although I am certain he doesn't visit this site.
He also noted 2017 PGA Championship venue of Quail Hollow as being near perfect at 7400, while noting that it only played max length one day of four, and that most courses actually play less than the max length quoted on scorecards in most tournaments, depending on wind, moisture, etc. That was similar to my comment regarding Sand Creek Station and the Publinx.
He also said he thinks most tour guys would go with a design like Harbor Town, with some length as being the hardest. Needs narrow fw to test accuracy, small greens, etc.
So, I will go with 7401 for the early over/under on TD's question!