The new Panasonic fz2500 is a camera that appears to be aimed at videographers rather than stills guys.
With is internal 4:2:2 10bit capture and its built in ND filters, alloy build quality, and tilting, swivelling touch screen it should knock the rx10iii into a cocked hat. Video guys will have little interest in the extra focal length of the Sony.
The fz2500 is aimed at pro's who will colour grade their footage, where as the rx10iii is aimed at amatures and enthusiasts.
(That's not to say that the Sony isn't very good, it is, it's just in a different market)
I've been told that the introduction of the rx10iii has forced Panasonic to hurry the fz2500 to market ASAP, and the fact that they announced it 3 months before it is available may indicate that they were worried about Sony grabbing market share. They've also priced it well below the Sony, which may force the price of the rx10iii down, (once stocks become common place)
Panasonic have also announced the forthcoming gh5, due mid 2017 which will be a big hit with video pro's.
One things for sure, it's great news for the consumer.