Rebuild - give me a break. 99 points with some great core pieces locked into team friendly long term deals, and we're heading into a rebuild? Please. Look at teams like Boston, Tampa, Vegas - they don't rebuild, they just reload. With solid ownership, management and coaching and a great young core, the Sens are in the best place they have been since the early/mid 2000s.
There's also an element of randomness to all of this for which we don't account. Let's look at Carolina - they were close for a lot of years, but not quite there. All of a sudden the guy universally pegged to be the third goalie and on his way out of the organization in Andersen goes on fire in the playoffs, and they hit on a great young prospect in Stankoven who was the product of salvaging a botched trade in getting Rantanen. Carolina has made some great moves, but sometimes you just have to be lucky and have all the pieces come together for you - it's the randomness of sports.
Different sport, but I'll never forget the fact that arguably the greatest NFL team ever assembled, the 2007 Patriots, lost the Super Bowl on the flukiest catch you will ever see in your life. Sports can be random, folks - that's why gambling on it is really dumb. Just enjoy the games and the chase...