https://youtu.be/Vb5E9VHuFjU
The major roadblock actually tends to be somewhere in the transmission or reception pipelines. Production fidelity also tends to be higher than what consumers get on their end so if guess that #ESPN's studio shows have been getting shot with #4K cameras for several years now.
I do tend to notice the difference between #4K and #1080p but that's just me I guess.