We don’t know much about the entry level and mainstream RV7x0 chips, but at least we got their names.
The lowest-end one is codenamed RV710, and this one should replace Radeon 3450 and 2400 series, powered by RV615 and RV620 GPUs.
It is followed by RV730 and RV740, and these two are set to replace RV630 and RV635 mainstream chips.
The RV770 is the ultimate replacement for RV670, the heart of Radeon 3870 cards, while the R700XT will consist of two RV770s.
This is what the line up looks like and you won’t see these chips before summer time, if not later.