New skirmish brackets will open up for those between Levels 71-75 and Levels 79-80. As mentioned before, Level 80 players will be able to participate in rated matches and be eligible for Level 80 Arena rewards that will, thankfully, look distinctively different from PvE gear. This means that players should be spending their Arena points now instead of banking the maximum 5000 points, as it will not carry over past Level 70. In this scheme of progression, Level 70 Arenas will conceivably die an eventual natural death.
What does this mean for the current season? When the pre-Wrath content patch is released, we're likely to see a shake-up in class representation in Arena play, as more classes become viable. It is also highly likely that the current season will end when Wrath is finally released, and competitive or rated Arena play will be in a state of limbo as Blizzard is likely to allow several weeks for players to reach Level 80 before starting a new Arena season.