IMO they need to no longer allow players on LTIR to be traded. Specifically those who are out indefinitely/forever. It is the only way to stop these trades. The cap was brought in to level competition, by forcing teams to all pay a similar salary for their roster. By taking on a cap hit that should be retired, the Yotes while technically are inching close to the cap floor, will actually be paying nowhere near it. Same for how the Leafs were able to dump Clarkson's contract to be able to pay a player who will never play again, and not count against the cap. Neither trade should have been allowed at all.
To be honest I don't really have a problem with the Clarkson trade, as much as I do this Pronger deal. Clarkson may actually turn out to be a useful player for Columbus. If they truly couldn't afford to pay for in and another actually turn out to be a useful player for Columbus. If they truly couldn't afford to pay for in and another quality player than this really is the best move that could've happened for them and for their fans too.
However, the reason the Floor was put in place was partially from cheating their fans. The coyotes trading for Pronger who is never going to play again just to reach the floor does just that.