This sort of statement can't really be proven true or false, because you put no time limit on it. Of course, eventually the economy will shrink instead of grow

This sort of statement can't really be proven true or false, because you put no time limit on it. Of course, eventually the economy will shrink instead of grow and you can claim to have predicted the future. In the same vein, during a recession you could predict a return to growth, and it'll probably eventually happen. Neither are particularly meaningful unless you give a hard timeline, after which we could declare you right or wrong.