For case(s) in point:

Grand Theft Auto V took more than 5 years to develop (and they didn't start from ground zero).

Fallout 4 = 7 Years (they started it after finishing Fallout 3, also starting with something).

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Not saying that I am an expert or anything, just trying to keep things "real"...

If you WANT a quality product; it takes more than throwing money at it to make it possible. Honestly, I feel like they are on track and they should take the time they need to do it RIGHT. Not FOREVER - just expect to see reasonable progress to final build, so far I have not been let down.

Taxman

"Any group is weaker than a man alone unless they are perfectly trained to work together."
- Robert A. Heinlein, Starship Troopers