I think the developer's ambitions are very realistic and fully achievable in a 2-4 year frame, rolled out piecemeal over that time.
What is probably unrealistic is some of the ideas we have of what the developers intend. When you're invested in a game's development it's easy to get carried away and imagine all sorts of frankly unachievable things, and then be disappointed in the actual results, even if those results are very good.
On the whole, however, I've been impressed with what FD have created so far, and every new update gives me more faith in the game. There are a couple of glaring omissions (passengers, salvage, etc) and some basic tools like a pilot's log and trading notebook in-game that really seem obvious by their absence. I still hope we'll get those things, and some other small features. However the upcoming 1.3 update should be terrific and the ongoing polish to existing features is good. I don't doubt their ability to give us a great planetary landing/exploration system (although it may look less photo-realistic than some people might imagine).
The first person expansion is the real dark horse for me. It will have to be meaningful, interesting, play smoothly and look good - and there is where FD may find problems. The Cobra engine is fantastic for designing a mammoth PG game (the big issue SC discovered once they got into production was that they were designing a space game on an engine designed for small areas - they addressed that, but it's still a problem that is only tamed by the comparatively tiny size of their game "board"). FD have the opposite problem - how to implement first person features using an engine that is not specifically designed for that purpose. I don't doubt their expertise in this area (The Outsider is proof of their creds), but it will be harder work for them than if they were using a 3rd party FPS engine.
