I genuinely feel like school in the US should be year-round but with a set amount of "time-off" teachers and parents can use. That way time off is not so concentrated in the summer, holidays can be celebrated regardless of ethnicity/religion/culture, and the curriculum does not have to be so compressed. I am sure there are a lot of challenges this model will bring up, but it feels a bit more fair.
In the meanwhile though, good on NY for adding Diwali as school holiday! It seems like a lovely celebration that should be enjoyed class-free.