I've been following the whole Aliens: Colonial Marines controversy, and honestly it just seems like a bunch of industry BS got dragged out into the spotlight.
I mean, it's my understanding that hiring a smaller independent studio is not uncommon, although I could be mistaken. But on paper, there's nothing wrong with that arrangement: a smaller company gets some experience under the oversight of a bigger (and presumably more well-seasoned) company (no different from hiring freelance devs except that you get a team used to working together, which is a plus for everyone). The firm employing them gets to manage their own resources more freely. The publisher requesting the project doesn't care how the game is made, only that it is made.
Of course, that assumes that there's some management involved to make sure whatever team doing the work is actually meeting their milestones. In the case of Aliens, that clearly didn't happen.
Secondly, of course previews are utter nonsense. They must be built separately for several reasons, including but not limited to how it's really hard/impossible to find a 10-minute chunk of game that accurately captures what a game is all about (cf movie trailers have the same problem) and how the polish comes at the end of the project, not when conventions are (a work in progress doesn't look terribly impressive, which is the whole point of a preview). It's been this way forever. I don't know what the solution could be, but we need to get away from the focus of launch day events if we don't want to be lied to by previews. (I personally try to stay away from previews as much as possible for this very reason, and have for years now.)
And of course contracts don't specify that a game has to be "good" in order for the contract to be fulfilled. I mean, think about this: in what way can you measure how "good" something is in order for it to be specific enough to be in a contract? That's right, it would be tied to Metacritic. And think of how awful that would be, if the game doesn't at least get a certain Metacritic score, then the development team gets sued for breach of contract. Yeah, that's not better. (Instead, Metacritic scores are tied to bonuses: c.f. the Fallout: New Vegas Metacritic controversy.)
All in all, I don't think Sega has much of a case against Gearbox (although that means pretty much nothing, since it's pure speculation from an armchair lawyer). The thing Sega wanted from Gearbox was a game, and Gearbox not only made good on their promise (after official, approved extensions allowed by Sega), but their hiring of a contractor to do the work will be seen as taking good-faith steps to see their contract to completion. Think of it this way: Sega could have denied an extension at any time, and dictated an absolute, final date, and started to enforce their milestone deadlines. Instead, they fostered an expectation that they would allow indefinite extensions. In all honesty, that's probably what Sega eventually did, at which point they had a crappy game, at which point they could throw it away or make some money by releasing it. (Although, it's odd that the word from Timegate is that they expected another delay, but that just may be disbelief that the game would ship in the condition that it was in. Still, that's more poor management, if the fact that time was up was not communicated effectively.)
So, in order for Sega to sue for breach they basically would have to prove that Gearbox knowingly and deliberately delayed the game in order to pocket the funds from the change orders. This is something that's incredibly easy to check (just look at a financial report), so the fact that Sega hasn't sued yet either means they don't care enough to jeopardize their relationship with Gearbox (which is doubtful: they most certainly would want millions of dollars rather than a relationship with a company who gleefully steals from them), or that isn't the case and Gearbox actually spent the money they got from Sega on developing the game. I doubt this as well, because I get the feeling that Gearbox would have been much happier had Timegate actually done an adequate job in the first place.
Although, one thing Gearbox may have done, which is touched upon by the latest whistleblower is if they took the money to make Borderlands and then took an equivalent amount of money made from Borderlands and put that into Aliens, which wold be questionably legal at best. That's an incredibly risky and stupid move if Gearbox did that, though.
All-in-all, the real failure here is management, and that's a delicate dance, because you don't want to be too overbearing as that could mess up the project as much as being too lax about meeting deadlines. Still, the bottom line was that things were going wrong, and no one did anything about it.