karnak1: If you look carefully at the game's updates you'll notice that the game isn't as ambitious (megalomaniac) as it may appear at first sight.
Honestly, it seems to be a more "story-focused Skyrim". Imagine Skyrim divided into chapters, with a more streamlined approach. The same way that Mafia 1 was GTA3 with chapters.
If they manage to mantain a good balance between open-world and linear narrative it may really work.
Plus, their budget does seem to not only be suitable for a project of that scale* and it seems to be growing too. That does give me some confidence. Time will tell, I suppose. Sometimes something comes along like that and looks amazing. But then you play it and it's all kinds of broken. Hopefully they'll stay funded long enough to polish it.
Alternatively, if I'm reading you right, they could always release it episodically.
*assuming that they're keeping staffing levels low and probably have some kind of profit share scheme instead of decent up front pay.