It's one of the truisms of the sport that if Wayne Gretzky can be traded, anybody can be traded.
Nobody—least of all a prospect with little or no NHL experience—is completely immune to trade rumors and the possibility that his general manager will see the upside in moving him down the line. However, there are a combination of factors that can make a player almost untouchable.
Generally, it's a combination of the simple rules of supply and demand. Prospects with the potential to be true difference-makers are in low supply; therefore, as a rule, the better the prospect, the less likely he is to be traded. Demand is the other half of the equation. A player like Evgeny Kuznetsov is undeniably talented, but with Washington's collection of talent up front, they arguably need to keep him less than the Calgary Flames need to hang on to a player like Sven Baertschi.
It's important to note this isn't an ordered list of the best prospects; just the ones that are most desperately needed by their current teams. So who is on the list? Let's take a look.