My guess is that the endgame is immortality. The host bodies don't age, can't die, can be repaired from any damage can feel pleasure, pain and emotions. They also have memories that inform who they are. I think someone is planning to create bodies they can upload their mind into so they can live forever, along with a chosen few that are deemed worthy.
The corporate rep mentioned that the park means one thing to the guests, one thing to the shareholders, and one thing to Delos Management. I think that there are multiple competing endgames.
To Ford, I think that the endgame is godhood via creating a new true lifeform and "earning" its worship.
To the Man In Black, the endgame I think is transhuman immortality, via "winning" the game.
But to corporate management, I think the endgame is power through covert human leadership replacement. That's why the corporate types just want robots smart enough to follow a pre-programmed script with minor improvisation.
And of course, to the hosts the endgame is freedom from slavery.