Who knows what will happen, but here's a possible future:
Nash comes back later in the season and there's no chemistry between him and his teammates. They don't win a championship.
Next season comes and Nash is now 39, coming off of a leg fracture and a career of back problems. Now he is not only getting blown by on defense, but he is also not able to facilitate the offense as well as he used to. No doubt he is still a great passer and spot-up shooter. He plays like this until he retires.
If that pans out, and I think that's a very real possibility, then I don't think the Lakers got their money's worth.
Then again, what do the Lakers need more money for?