From what I've heard 5.0 will only be available on the 8330, the development on the 5.0 os for the other 83xx's have terminated their development a while ago.
It's unlikely that there will be a complete update for non 8330 83xx's. Probably update some non-core apps like BBM to create an official hybrid. They will get OS 5 out for all devices that can support it immediately and then perhaps go back and see if they can shrink for the smaller memory 83xx's.