You're trying to have your cake and eat it too. The salary cap exists, and players get injured. That's all just reality, and part of the game. If the player on LTIR comes back for the playoffs, you simply have to sit the players you acquired to get by while he was out. That's still a rule that's completely fair to all team equally. If there's too many good players sitting during the playoffs, that's a result of dilution, not the closing of salary cap loopholes. The actual catalyst to most of this problem is that it's questionable that a guy gets 'healthy' at exactly the right time.