Millennials are just a group of people. They don't all think and act the same way. There's still a much larger group of people outside of millennials that could support these businesses. Anyone over 35 is not a millennial, but they're not showing up anymore either.
Business's blaming their problems on one group of people is just an excuse and failure to recognize their issues. Millennials aren't the only ones not showing up to NFL games, just like they are not the only ones not eating sh!tty overpriced food, and ordering from Amazon.
My gripe is that nearly daily now you see a new article about how millennials killed a business. No, their sh!tty, outdated, poor product, and poor leadership killed the business, and a new business took their spot. That's the way it has always worked, it's not just millennials killing things.