Yes, PIP seems to have dropped off the face of the planet - certainly as an Advertised Feature.
Perhaps because (at least in the states...), the majority of viewers no longer get their signals OTA??
Some "cable" tv providers offer some sort of "PIP" - with Uverse, for example, we get a tiny "preview" screen when scrolling through the Guide.
Uverse also has a "multi-view" option that shows one main active window, plus several others along the right edge of the screen that you can scroll through and/or swap (individually) into the main window.
Beyond that, have read that some sets have (or will have - ??) capability of showing two different video streams at the same time by using the 3D - but in this case ONE viewer would see Show A while the OTHER viewer would see Show B.
Also recall reading that the new Really Wide Screen TVs (21:9), can show Content along the edge of screen - instead of Black Bars - when viewing 16:9 (or narrower??) programming.