Yeah i'd agree here that GTA is not a shallow game, it's got multiple levels of openworld interactions that you can chose to interact with or not.

What it doesn't have is strict or difficult obstacles that give a perceived difficulty. The game's difficulty hits a plateau quite early on and then it's really an exploration and narrative experience. Which most people prefer. GTA online is a different beast and probably where this one will focus. More live ops and changing / persistent world, more like fortnite's map would be my guess.