You can't laugh at his predictions based on the present situations yet somehow out of nowhere suggest that both Chelsea (drastically) and United will improve themselves in such a manner that they'll be top 4 certainties next season, because that's also based on nothing.
You don't know what the transfer market will bring, you don't know how your coaching situation will look like in August, so it's basically just all speculation. In the here-and-now, the top 4 will be unchanged next season because no team outside of it is good enough right know to sneak in. And yes, you can be 99% certain it will be different after the transfer window but right now you can't just guess United and Chelsea will replace Leicester and Spurs because they're the richest teams or whatever grounds you're basing your prediction on.
No, I'm just laughing because it's typical Glaston. He mentions Liverpool because he does that everytime to wind up United fans. If that conversation was with you, he'd be belittling Liverpool then, it's how he rolls. He's been saying shite about Liverpool for a while putting Spurs miles ahead of them but when it comes to this prediction he's fine putting you in top 4 because it's a good wind up.
It's not impossible Liverpool will finish ahead of us next season, I actually think you may well do that. You have superior manager and some decent talent.