So, Trump is the cause of the tarriffs going up to 40%. Now he's claiming (and since it's Trump, we have no idea whether it's true) that China is going to (some time in the future) lower the tarriffs again.
Let's file this in the "I'll believe it when I see it" department -- the 40% tarriffs are still in place as of today -- and also in the "proably returning to status quo ante" department -- China will probably end up with the tarriff level they had before Trump started shooting his mouth off about tarriffs.