The same thing was said about Mike Portnoy, just sayin...
Not that I want them to replace James, he’s amazing, but I don’t buy the “it wouldn’t sound like DT anymore” thing. Bands change members all the time, some more than others, but it happens anyway, and I believe the only irreplaceable DT member is JP. If James ever left and they get a great replacement, it would sound different, yes, but it would still be and sound like DT.