Keep in mind that the codenames below are the microarchitecture names, the actual chips these cores will be used in will likely still have Lake names. For example, Intel said at the event that Ice Lake will use Sunny Cove cores.
Sunny Cove is a 10nm product and it will be the biggest change to the Core lineup since the launch of Skylake. You can expect higher single-threaded performance, new instructions, and improved scalability.
In 2020 we can expect Willow Cove, this architecture delivers a redesigned cache new transistor optimizations and new security features. Golden Cove will follow in 2021, that architecture will feature single-threaded performance optimization, better AI performance, a networking/5G performance uplift, and more security features.
AnandTech has a nice write-up with a ton of details over here.