I don't think that the neopixel could be used as a primary source of light at that distance, but what about supplemental lighting?
My "gut" says no, but I suppose if you have enough of them...
I did some rough estimates/calculations and I'm going to say it takes about 1200 LEDs to give you the equivalent of one 75W halogen floodlight. That could be off by a factor of 2 or more but it's a start... And that's assuming all of the LEDs are on at once.
...I'm not sure how to interpret the mcd brightness for an RGB LED. I averaged the midrange of the 3 colors. That may be pessimistic.... Maybe they sum (rather than average) to get a white equivalent And the mcd to lumens conversion (which I found online) asks for an angle. I assumed 90 degrees and that might also be pessimistic.
..I've got a sound-activated lighting effect that uses (only) 48 regular red "high brightness" LEDs. I consider that a "special effect". My "primary effect" that's intended to "light up the dance floor" uses 8 100W colored incandescent floods.