Is Sidecar obsolete with the introduction of Universal Control? Are they meant to coexist with switching between the two?
Universal Control and Sidecar
It seems to me that the two features accomplish different things, and are complimentary to each other. Universal control allows you to use your keyboard and mouse to control iPadOS. Side car extends your Mac screen onto the iPad as if it were another monitor. I don't work at Apple, but it doesn't seem like one feature would replace the other.