Over the weekend Apple confirmed that the iMac Pro has been discontinued. Devices will continue to be sold until supplies run out (via MacRumors).
The Ballad of iMac Pro
Introduced in 2017, the iMac Pro is a 27-inch Retina 5K display with features like 10Gb Ethernet, 1 TB SSD, a 3.0GHz 10-core Intel Xeon W processor, and a Radeon Pro Vega 56 GPU with 8GB HBM2 memory.
For now, Apple recommends people get the latest 27-inch iMac instead. But the company is expected to release a redesigned iMac this year running an Apple Silicon chip. Rumors say it will be based on the Pro Display XDR.