What is present or important now may be absent or irrelevant in the future.
here today, gone tomorrow
Lacking permanence, fleeting. For example, His book attracted a great deal of attention but quickly went out of printhere today and gone tomorrow. Originally alluding to the briefness of the human lifespan, this phrase was first recorded in John Calvin's Life and Conversion of a Christian Man (1549): "This proverb that man is here today and gone tomorrow."