This is answered here:
http://us.battle.net/wow/en/blog/2880562Arena and Rated Battleground Season 9 is scheduled to end as early as June 28...
...At the end of the season, Conquest Points will be converted to Honor Points, possibly exceeding the 4,000 point Honor cap. All Season 9 items will cost Honor Points (equivalent to their previous Conquest Point cost) when the season ends, with the exception of any items with rating requirements attached. These items will no longer be available for purchase.
The next Arena and Rated Battleground season will begin for level-85 players approximately one week after the end of Season 9 and will coincide with the awarding of Season 9 titles and mounts. At that time, any Honor accrued above the 4,000-point cap will be converted into gold at a rate of 35 silver per point. In addition, Season 10 rewards will be made available for purchase with Conquest Points awarded during the new season.
If you have a question about any of the patch 4.2 features or changes, our patch guide is a great place to start:
http://us.battle.net/wow/en/blog/2723732