Chances are the 4000/5000 series will be priced either the same or slightly higher than what their nearest equivalent 3000-series counterparts launched at, so the 4600/5600 will probably land in the $230-250 range at launch.
The 2600 and 3600 both launched for $200, so there's a fair chance the next 600 model will launch for that same price as well. Even the original 1600 was just $220. So, probably more in that range for the base 6-core, 12-thread model, unless they feel there are more substantial performance gains than the 3000-series brought to justify higher pricing.
It seems a bit less likely that a new 12-thread part would launch for less than $200, but you never know. Intel's Comet Lake processors now roughly match AMD on core counts, and the i5-10400 is widely available for just $180. So, it's possible AMD could match that processor's price. If their new chips are notably faster though, they might just drop the 3600 to a lower price point to better compete with that. After all, the 3600 had already been priced under $175 for much of this year, even dropping to around $160 at one point during the summer, so seeing that drop to around $150 or so could happen, especially during holiday sales. This is for US pricing, of course, as prices could potentially be different in your area.
As for the release date of the new processors, it's hard to say. It could be at the announcement in a few weeks, or it could be some weeks later, perhaps alongside their new high-end graphics cards. I haven't heard any rumors about a specific release date yet, but I would think it would probably be later than the announcement date, as otherwise everything about them would get leaked by retailers beforehand.