Given the repeated delays and the drama among the animators and QA I’ve been hearing about, I’m worried too. Though similar things about Uncharted 4 were reported after its release and that turned out fine in the end, so we’ll see.
The games industry is a tough business. Filled with young people working long hours for low pay - which tends to happen when more people want to work in the industry than it can support. QA is a hard job, requiring lots of time but not a lot of skill or training. From my perspective (which is very very distant) it seems like a lot of companies and hopeful employees are viewing QA as a foot in the door for moving into better things. We can debate whether this is a good idea or not, but it is a recipe for drama.
So the scenario with a modern, big budget game is that you have tons of people with access to the game, including near finished product, many of whom are overworked and underpaid. Some of those people are mad about it, or just desperate for a quick buck. Which means leaks.