The thing is, though(I think i read about this idea in A Briefer History of Time), being a truly random process, occasionally it’s going to have a period where it appears to exhibit ordered behavior. It won’t, but if a given ordered process is possible, a random process will eventually behave very much like it. This may cause a bunch of particles to jump all to the same place, without other particles jumping out to make room, and staying there long enough for gravity to reassert itself. Over time, the macro level effects of gravity(and other forces) will dominate over the quantum weirdness, triggering a gravitational collapse- everything in the even field will be pulled into this point gravity source. It will get bigger and bigger, squeeze tighter and tighter, and then Big Bang.
Granted, this isn’t certain, but it’s one of many possibilities of what may happen. If Bill has some guts, he could move for dismissal as there will never be a situation where he’s in danger of breaching the contract. There will be a universe in which the debt can be paid and things in this universe will be able to be collected into a suitable payment, forever. Though John could counter on grounds that the information about the debt would be lost, rendering Bill entirely unable, even in principle, to ever pay up. But at the very least, a continuance until heat death(the first time) should be possible, though Bill may be required to take special measures to ensure his heirs remember his obligation.
Wonder why legal language is verbose and painfully precise? This is why. So smartasses can’t pull bullshit like I just outlined here. There’s also vast bodies of case law we keep around to help deal with these sorts of absurdities, I’m sure something in there would prevent “the end of time” being the payment period unless it was explicitly specified.
Realistically… Unless the judge decided that adjudicating the contract itself does not count as a win for the purposes of the payment clause(not a lawyer, so I have no idea if this is realistic), Bill’s going to be paying up either way it goes.
