There was a leaked tidbit but no one knows if it was fake. Oh and a rumour about a benchmark? or something to show that it was at least a rumour.
I've heard summer so you have a couple of months at least yet. I've also seen that in multi threading the 2700x beats the 8700k quite handily and has closed the gap in gaming so you can 100% expect it to definitely happen. I would imagine it will launch with Z490, and *may* only be compatible on that, depending on the power phases on existing Z470 boards.
If not it may well release sooner. There is no way Intel are going to leave it now, they are clearly beaten on performance and price. Then things may go quiet for a while. Once they put that 8 core out there they are certainly not going to want to give you anything more than that until Zen 2.
D read this mate.
https://hothardware.com/news/intel-technical-docs-appear-to-confirm-8-core-coffee-lake-s-processor