It's true that Thanksgiving isn't a Holy Day, but it IS an American "holiday" where people take time off work to spend time with family.
It just seems like the force of commercialization marches on, constantly pushing the boundaries.
It's undeniable.
To give you an example of concrete progress they have made: Just in 2013 companies started having Black Friday deals throughout the whole month of November.
I can say accurately that as of right now, the Christmas shopping season starts the day after Halloween, or November 1st. They might have a hard time getting it to start before Halloween (let's face it -- the ambiances of Halloween and Christmas are pretty much opposites!), but I have seen Christmas stuff in some stores as early as September.