Keep your cpu and wait till 3000 launches at computex in june. AMD Ceo has said in an interview that 7nm ryzen cpus with more than 8 cores are coming. Although she didnt specify he many cores, early an 12 core cpu 7nm ryzen benchmark has been leaked. By design, in order for there to be a 12 core ryzen cpu ther must be 2 8 core modules on the cpu, meaning a 16 core will come. AMDs 3000 series cpus will work with existing Am4 motherboards. You will likely need a bios update in order for it to function, but it should work well with any ryzen 3000 cpu, including ones with more than 8 cores.
AMD CEO Lisa Sue said in an interview: "So there is some extra room on that package (the package of the 8 core 7nm ryzen cpu demoed at CES 2019). And I think you might expect that we will have more than eight cores. I didn’t say how many more."
I would hold off and wait till June when they are said to be announced. They sound promising. For example, AMD demonstrated an 8 core ryzen 3000 series CPU at CES. The chip was an early sample so performance WILL improve in the release version. Yet still, the 8 core Ryzen 3000 just barely beat the 9900k in cinebench while using 30% less power. If an 8 core ryzen 3000 beat the 9900k while consuming less power, just imagine how the 16 core Ryzen 3000 cpus would perform.