Full backlit LED sets with local dimming have always been "rare". Sony made the XBR8 and currently the 929 series.....Samsung made the 8500......LG made an 8500.....and Vizio with the 553 AND 554.
The 553 sold like hotcakes due to good reviews and exellent price.
Edge lighting may be getting better, but it will never match a fully backlit set with local dimming in terms of PQ.
Manufacturers make more money off an edge lit set with fewer LED's. They can make them super...