WRONG.
There 100% better chance you get him next summer than now. There is zero chance of him leaving of any amount of money this summer. But after the world cup is a different story. If he has a successful world cup then he will be off, well 85% likely to be off.
I'm no Liverpool fan, but let me state my case:
1) It is easier for him to get into our team now, so it would make sense for him to want to leave now rather than later, because we could get other players and end up not chasing him next year (good for Liverpool, but not Coutinho).
2) Liverpool are going to have a better season next season than the last (they play champions league, have a better chance of challenging for the title because of more time with Klopp + signed Salah etc.). Therefore they will have a stronger case of convincing him to stay longer: "The differences between Liverpool-Barca isn't that big" etc. - those arguments will weigh more next year.
3) When have Liverpool said no to 100M€? I mean, I get that no one wants to be a selling club, but even Tottenham sell their players in their prime (Walker) even though they have the best chance of a title in decades (bigger than Liverpool, imo).
So if we agree that Coutinho wants to be at Barca and not just some random topclub (Bayern, PSG etc.), then his chances are better this year than next year, and I think he also know that.