I am guessing this is what your talking about I've seen and alliance and horde cave on opposite sides of Forlorn Ridge. This is a good bet where the new BG will be. Which is nice as it is near both flight points.
A future Battleground in Azshara. It will most likely be in southern Azshara, in the Forlorn Ridge. It is intended to work in a similar fashion to Alterac Valley.
Battleground Entrances have already been placed within the zone, with the Alliance entrance on the south side of Forlorn Ridge, and the Horde entrance on the north side of Forlorn Ridge. They are currently inactive, as the Battleground itself has not been implemented.
It is rumored that Azshara Crater was put on hold because of difficulties balancing Alterac Valley and how Alterac Valley did not turn out exactly as they intended. Now that Alterac Valley appears to be at a point that the developers are more or less happy with, Azshara Crater may be worked on once again.
Rumor Breaker!
The battleground, or at least early rendition of it, can be accessed through WoW Mapview.
The area is divided into three distinct parts. The first one, where the only visible entrance seems to be located, has a fortified camp made of a peculiar mixture of orc and night elf architecture. This might indicate that the battleground was intended for an allied battle between joint forces of Horde and Alliance and unknown enemy.
The middle part has camps of furblogs, and a small cave on the side.
The final part, marked by the entrance adorned with two massive dragon statues, has a huge high elven structure, purple in color, surrounded with other highborne ruins, resembling somewhat the Naga temples in the eastern part of Azshara.
Azshara Crater is an unreleased Battlegrounds instance.
A large, unreleased PVP battleground. Azshara Crater is also known as PVPZone2. It will most likely be in southern Azshara, in the Forlorn Ridge. It is intended to work in a similar fashion to Alterac Valley.