If you look at the measurements, this is provably false. 2011 Panasonic plasmas had a slightly better black level than the Sony Z9D and comparable to the best LCDs. The last two years of Panasonic and Samsung plasmas, and in particular the 9G Pioneer Kuro and the VT60/ZT60, have better black levels than any LCD to date. Now that said, I have both a 9G Kuro and a 65B7. The Pioneer is voltage-tweaked and looks amazing, a slight glow in a black room, but inky black on mixed content. It's only aside the OLED that you notice much of a difference.
The Pioneer plasmas actually crush black more than Panasonic ones. Panasonic has great black detail, probably even above reference? OLED crushes black a little too. That never stopped the Kuro from being the industry's consumer reference display for like 5 years running, or OLED for the last 3, but it is notable as a flaw for these displays.
They'd cannibalize lots of their own sales for the first half of the year. But yeah, it might be worth waiting unless you are trying to swap inside a return period or something...