Function Reference/human time diff for future posts

You could also do it using human_time_diff hook, but it would make it global:

function my_time_diff_mins( $since, $diff, $from, $to ) {
   return $since . ($from > $to ? ' from now' : ' ago');
}
add_filter( 'human_time_diff', 'my_time_diff_mins', 10, 4 );