Seriously, I doubt it would even take that long. We get used to shit so quickly, and the news cycles have to keep feeding us new things, the only way we’d keep talking about the aliens if they kept doing new and interesting things. I’d be willing to bet a year later there would be some people who straight up forgot about it. “Oh yeah, aliens! Are they gonna, like, visit at some point or just keep exchanging calls with the Whitehouse?”
People as a collective are incredibly stupid. And because of this they’re incredibly easy to manipulate. It has always been this way- it’s just that now, the powers-that-be have figured out exactly how to use them to a perfect advantage.