How long's a piece of string.
It depends what you mean by “last”.
Do you mean before they break down, are dead and aren't economical to repair?
Or before the pictures deteriorates and is unwatchable?
My 10 year old TH-37PX80B Plasma was still working with an acceptable picture when I sold it locally for £50 last November.
Some later Panasonic Plasma's weren’t as reliable but at the end of the day it's down to pure luck.
my 42phd8 is still going, its in the dining room and the mrs uses when she is using her sewing machine. not reallly done a side by side comparison but the motion is better for sports on the plasma than my samsung 4k tv
My 2007 Fujitsu P42XHA58EB (which utilises a Panasonic panel) is still going strong - with the addition of various HDFury devices over the years it has stayed 'compatible' with any Source I want to use it with.
I had g10 I am not sure when I got it , propably 2009-2010 . I gave my friend last month, everything is ok with tv.
From other side I have much younger p50gt60 , last launched panasonic plasma ,
There are white dots in startup tv