Yes, FDev had the plan and outlined what they want to do. You always make changes as you go through a multi-year complex project. The whole industry is changing with new hardware/software-engines/social preferences. A good company will always adapt to a new environment and learn from mistakes of others.
Take CIG for example. They promised everything in 2011 (I remember when they started the campaign). By now, we should have 100 star system, a lot of planets with cities, etc.
Now, let's look at FDev. We have a finished product which many enjoy to play. They came up with two new DLCs that significantly enhanced player experience. I bet they have something else in mind (I hope for one-two cities where you can buy a land plot and build your own place in earth-like environment).
Modding. There are graphical (I changed the HUD to blue) and voice mods (HCS) approved by FDev. There are many 3rd party tools (eddb, Inara, etc.) that get data from FDev files (not only but some). The problem with modding is obvious: you can easily allow modding in a single player game (such as Egosoft X3, X4); however, if it is a multiplayer and different players run different modes, it can completely screw the game. Another side of that, any game update may screw custom mods installed. I am playing one game which is heavy on mods and players are shouting load with each new update, even though the updates are really good and even free.
Interior-exterior. We have ship, FC, station exterior and I personally like it. We have station, FC and land base interiors. We do not have ship interior and it is actually very good. I played games with ship interiors and it does more harm than good. First of all, two games came to my mind (X4 and SC) , the interiors are buggy. You have to make a proper mash for all available ships (a lot of work). There is no meaningful interaction but open and close the door, press the pilot seat. When you are not in a pilot seat, you may be kicked out in an open space when the ship is moving and you die or worse get stuck in the "interior". I got kicked out of a small fighter cockpit when I tried to put three cargo boxes inside - apparently there was no room left for me. I could not do much as to grab the third box and throw away I needed to enter the ship.
What Fdev could focus at is doing some extra work on FC interior. It is just one ship, everyone eventually will have one. It can be done very nicely with some extra rooms for decoration. It can bring a lot of real money to the company. Players can buy for ARX the extra rooms that have nothing to do with performance but decoration mainly. I guess NMS approach (a lot of options to build inside your FC, no other ship interiors) here proved to be the right one instead of SC - so many ships, so many interiors, so many bugs, the game will never go to Beta.
Odyssey was the right step and it makes a strong foundation for the future game expansion upon. FDev promised and deliver.ed. Is it good? Some like it (including myself).
FC is great that you can get all (at least 40) your ship to land and be stored at. So again it is done in one form or another.
The only thing is really missing is cities. I would not go for a full universe but it could be just one-two well designed cities. Or there is an alternative, just dedicate one planet (Sirius? or Mars?) and sell land plots there and come up with pre-fabricated modules to build whatever players like (lego style).