I'd like to say I'm grateful Shenmue 3 is releasing during the late summer/early autumn window they chose after watching so many big budget, heavily marketed AAA games get thrown out into this crazy holiday season and perform poorly in the shadow of Red Dead Redemption 2.
Battlefield V just came out to weak pre-orders that forced EA to delay, and can already be had for $30. Fallout 76 is $35 - $40 a week after release (though a lot of that is due to it being in terrible shape). Just Cause 4 isn't even out yet and can be had for $35. On the Deep Silver/THQ Nordic front they've got Darksiders 3 coming out today to middling reviews, where it can also be found for $35 and it will likely get crushed. That last thing I would want is for Shenmue 3 to get buried in this overcrowded market.
This spring wouldn't fare much better with another overstuffed release schedule including Resident Evil 2, Kingdom Hearts 3, Crackdown 3, Metro Exodus, Anthem, Devil May Cry 5, Sekiro, Days Gone, and The Division 2 all competing for mind share.
Obviously, the fall and winter 2019 release schedules will fill up after E3 next year, but I doubt many publishers will jump on August as a target release month for their big budget games. They never seem to learn their lesson and continue to leave the summer months mostly empty, while trying to force marketing miracles in the face of bigger games for the holiday shopping season. I suspect that while YsNet is grateful to have the time they need to polish the game, a large part of the release date decision was trying set themselves into a window where Shenmue 3 can stand out.