I think AMD is changing their strategy now since 28 nor 32nm processes are going to be viable this year at all from either Foundry Company or TSMC. The intention is to use Southern Islands to compete with GTX480 and its possible refresh. I highly doubt there will be any refresh of 5870 series at this point. Looks like a "hybrid" northern islands and evergreen card (or 3 of them rather) are going to come out in 2010 and 2011 is when 28nm new gen will arrive:
http://www.xbitlabs.com/news/video/..._Different_Suppliers_Hybrid_Architecture.html