The number of SB850 chipsets aren’t enough to meet partner demand and the reason is said to be limited capacity of the 55nm node at TSMC. This is said to affect the launch of SB810, a cheaper version with limited RAID functionality.
The solution several motherboard makers are contemplating is using the older SB710 southbridge with the newer northbridges. Though this will limit functionality and future potential.
We can only presume that these SB710 will be targeting the entry level segment and something you will easily spot in the specifications. We can’t really recommend anyone to buy a new AMD motherboard and not get the excellent SB850 southbridge.