I'm watching this iMac announcement and .. hm, I still find it underwhelming. The top-spec'd iMac will be less powerful (when it comes to CPU) in Jan/2018 than my current desktop I bought in mid-2015. We'll see the actual pricing though. I don't think that forcing high-perf components into a small desktop chassis makes a lot of sense, but it might me only me.
Your current desktop has a more powerful CPU than an 18-core Skylake Xeon?!