So, It goes back to the old saying: A band's as good as its drummer.
Originally Posted by Deltadrummer
Quoting Geddy Lee, "This is the band, these three guys, there is no replacing anyone in the band. "
You can't replace Mike Portnoy in Dream Theater. Whoever they would get to take his place while on hiatus would be temporary for a year or two. And if the members of the band don't address it like that, they are really deluded, and a bit short sided.