It's an interesting question, the thought has crossed my mind also...But I think you're over thinking it. After all, we're Beeks, not Bee gods! :)
In the big scheme of things the fate of those 2 hives are insignificant to the big picture. Think of the number of hives such as those that get sprayed on a daily basis that we never even know about.
By all means, I think we all should try to 'do the right thing" but agonizing over, and bringing the posibility of future land sales and lifespan of structures into the equation, is probalby a bit much. :)
I'd say, keep it simple, if you want the bees, do the cutouts...Properly and in a responsible manner, making every reasonable effort to save the bees. If it's more trouble than it's worth, walk away or do some swarm traps instead, if you'd like. But I wouldn't lose any sleep over it either way. At the end of the day, NO ONE knows if the life span of those 2 colonies will be longer in those walls or your hive boxes.