--A major U.S. pro sports franchise suffers a tragedy similar to the 1958 Munich air crash that devastated Manchester United.
All four major sports have a plan in place to resolve this kind of situation (by the by, not that it's a major US franchise, but for another example of this, you need only look at the Lokomotiv Yaroslavl plane crash that occurred in September of 2011.)
The plans are, IIRC, not all for public consumption, but they do exist. There was a TL on here by TRoehl, called 1992: MLB's Black Wednesday in Atlanta, wherein the Pittsburgh Pirates suffered just that kind of catastrophic accident. (I went to look the thread up, since it's worth reviewing if you're interested. It's a damn shame that it was never completed; for that matter, it never made it to the disaster draft. There was some great discussion, though.)
When that thread came up, I did a little digging into this, since the plan intrigued me, and while I couldn't get much on MLB's disaster plan, here's what I did get:
MLB's disaster draft kicks in when either 5/6+ players from a team (different sources give different numbers) die or suffer a career ending injury at the same time. Every team submits an unknown number of players to the league that would be protected; the drafting team selects from the unprotected players until they refill their roster. It is not clear, but it seems likely that the rules stipulate that only one player from a given team may be selected by the drafting team, after which all the other players from the team losing a player would come out of the pool.