after the destruction the fruit will also disappear from jerusalem.
but the eggs status remain the same.
everyone who lives within 1 day walk of Jerusalem had to bring their 4th year fruit had to Jerusalem, to keep the markets stocked with fruit. after the destruction this no longer happened. Rabban Yochanan b. Zakkai did not revoke the decree about eggs laid on rosh hashana, but kept it in place, as the Temple might be rebuilt and not confuse as the egg was eaten last year.