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?”
I just strongly doubt that. Firstly, heaps of people would be dressing as aliens for Halloween and thus talking about it.
Secondly, there’s just way too many follow up questions, about them, their culture, their home, their tech, their goals, their language, their biology, the impact they’ve already had in our history, who knew and who didn’t, etc.
So many fields would begin looking into it and throwing up new angles and facts for people to chew over.
Just think of how much time christians would devote to converting aliens to jeebus.