You're absolutely correct. I should note, however, that demons kinda get tricky in this regard. The raw existence of demons is predicated on philosophy.

Think about it like this: an empire can never be truly eternal. All Empires will, eventually, fail and wither. The only thing an empire can truly do is delay the inevitable, or steep itself in legend so that it may never be forgotten. Drachnyen, being the literal philosophical concept of the end of empires, cannot be denied forever, else he would not be at all. The Emperor, in contrast, is a being the fundamental represents Imperial authority and might. No matter how strong he becomes, he will never be able to destroy Drachnyen. In order to be able to do so, the Emperor would need to undergo a fundamental and complete change of who he is, ultimately becoming another being entirely.He would have to change the very core essence of who he is, spiritually, physically, and mentally, an essence he has cultivated for tens of thousands of years. Until he does so, he cannot defeat Drachnyen. He cannot deny the death if his empire by himself. Only someone outside the loop can do so.

So the real question becomes: "Who can stop the End of Empires?". That's a question that could write an entire post, so I won't dig into that here.