My understanding is that it was going to be very difficult using plasma tech to build individual pixels small enough for 4K on typical sized TV's for the home (55-65 inches). I am not very well versed in the exact technical challenges, but that is my foggy memory of why only the very large Panny 4K plasma panel were ever produced, and none were sold to consumers.
Plasma was killed by the advent of 4K, image retention/burn-in fears, and lack of brightness compared to LCD in the store. RIP.
FYI, I still love my ZT60....even though it is enjoying retirement in my parents living room now.
Yup, I got stuff...
LG OLED65C7P, LG 55EG9100
Marantz SR6012, Outlaw Model 5000, Oppo BDP-203
PSB Synchrony Two mains, center, and surrounds, 2x SVS SB12-NSD
XBox One X