Deeper black levels, brighter, less energy usage, etc. etc., just like every year. I'm sure it will inch ever closer to the Kuro, and the folks who said this year that they'd wait until 2013 to buy a Panasonic will say they'll wait until 2014 to see what improvements are made.
I feel like Panasonic made large strides in design and picture quality this year over 2011 models, so I am not too sure that 2013 will see a ton of advancement. I just hope the VT60s are not too great, because I'm very happy with my VT50
Also, I think larger sizes wouldn't hurt. I've been selling way more 70" Sharps this year than I did in 2011, and fewer large plasmas. 65" simply isn't big enough for many people nowadays, especially those upgrading from large RPTVs. I don't know if it makes economical sense to mass produce 70"+ PDPs, but it would definitely get them a spot in a market where Sharp has no competition.