Of course depending on how it's written it is possible there could be some room for interpretation, which would likely end up being litigated, but I suspect these huge companies have teams of lawyers that are pretty careful about that kind of thing.
As a negotiating tactic, if they really want and need to retroactively rewrite the contract they can say 'This is going to happen. You can agree, or we can spend money to destroy you legally and/or otherwise'. It depends on how badly they need to change the thing, but the amount of abstracted power they've got should they choose to wield it is enormous. At that point it becomes a game of personalities: does the CEO want to go to the mat on this one? Will the board go along? Bear in mind that shows of strength and ruthlessness will help the stock price, because those evaluating Apple for what it's worth are only interested in ruthlessness and power.
I think it's very silly to consider that laws mean anything anymore. In practice, only money matters. (in fact I don't approve of this, but that's my evaluation of how things stand, and how we got here)