When you develop software you divide features into things you must have, things you would really like to have but could do without, and things that it would be nice to add if you get the opportunity.At this stage of development, they've been working this since like 2017 at least. At the very least they know by now what is planned for being in it.
And, these days, things that would be good to hold back for DLC.
Also worth noting: 2 years is a very short time to have been working on a AAA game. 5 years isn't unreasonable. If they get it finished in 3 it will either be very impressive, lacking in features, or a mess of bugs.