Unless the Flyers use all their Cap Space at Regular Season's end, at least some... if not all... of the bonus will be taken care of in 2014-15. A team cannot go over the Cap, so it's either under or directly at it... How the LTIR allowance is taken into account in this matter, I'm not sure about. Possibly Pronger's LTIR allowance might come into play and how this all is effects how the Bonus counts against the Cap depends on the way the CBA is written... which I'm not aware of.
But again, as I see it, Hexy has some added UFA flexibility and options with the Bonus dollars being there rather than in the contract and against the Cap... and the PreSeason over the Cap allowance is not eaten into as much. So no matter what, it does help in being able to sign players to the roster before the opening roster and Pronger's being placed on LTIR, when $2M is not counted against the team.