You implied that if we kept New Horizons going, that we would get more Pluto pics. I would love for that to happen however it is physically impossible for New Horizons to turn around to see Pluto. It simply doesn't have enough fuel to negate its over 10,000 mph (16,000 kph for you metric folks) speed relative to the sun and then accelerate to that same speed in the opposite direction.

The only place New Horizons is ever going is beyond our solar system which has tons of cool science involved by studying solar winds near the heliopause but unfortunately no cool pictures. Also, I am not a scientist but I am not sure what data gained from solar winds study would be new compared to what was already provided by Voyager 1 and 2.

If shutting down New Horizons means costs savings that allow a new probe to be sent to orbit either Uranus or Neptune, which haven't been visited in decades, I am all for shutting down New Horizons.

If Pluto is still a planet, do you also count the other dwarf planets as full planets? If you count Pluto as one you kinda have to count Eris as the 10th, but do you also consider Haumea, Makemake, and Gonggong to be full-blown planets?