Blizz has recently stated that they are thinking about adding the possibility to earn those silver coins when fighting pet battles (instead of having to do dailies to get them). In addition, if you are below lvl 90, you will earn xp on your character eaqual to killing a yellow mob.
Other than that, you get to have fun doing PVP battles where you tailor a lot of different teams with synergies.
On the horizon, we will get more pets to collect (although probably not as many new ones as 5.1 gave us), enable us to upgrade our pets to epic quality (good lord, we would have to aquire a LOT of battle stones for this, and we would probably lose 2 levels when upgrading our current lvl 25 rare pets to epic quality). That should give us something to do
Blizzard also considers adding "boss" pets in the wild, where you use your whole team to kill one powerhouse pet. Only issue I have about this is that the "boss" pets probably would be heavily camped, and on PVP servers it would be like fighting for the chest in an arena; interrupted from being attacked all of the time. If I have to camp for hours to get to do a boss pet battle, I'm out. Likewise if I can get attacked while battling it, pulling me out of the battle and the pet dying from some AOE during the ensuing PVP battle.
If you look at the pet battle GUI, it is separated into two sections, divided by a "bar". The buttons are 3 pet skills, pet switch, capture and forfeit. There are room for two additional buttons on the far right. Whenever I see something like that, I immediately think that Blizzard has implemented it for future use. Perhaps they will add consumables to pet battles like health / dodge / dmg-potions (hope not - that would make them mandatory). Or perhaps they will open up for leveling past lvl 25, giving the pets additional abilities. Who knows...
It's not long before I don't really need any more soulbound pet battle stones. After that, I only need to do PVE battles to level pets (which you also can do through PVP, which has been buffed xp-wise). The rewards for PVE battling are too low to bother doing that, which means PVP is the way to go. PVP doesn't really give much either, other than having some fun with your teams. Would probably become tired of this after a short while. I'm not too interested in the silver coins, but if I received valor points from PVE battles (such as pet battle dailies in the least), and conquest points from doing PVP-battles, I could at least upgrade my character's items as a bonus.