The future will undoubtedly bring a formidable foe to the Burning Legion.
However, Diabolo was not overly worried. It's just a hero who can turn into a dragon, after all. When the Burning Legion arrives, the Ancient Dragon King, the Golden Tree, the Centaur Emperor, all will be merely waiting for death.
Keep in mind that both Archimonde and Kil'jaeden are third-order End of World beings, and Sargeras is a transcendental entity. If not for his power being too overwhelming to enter the Prime Material World, Azeroth would have already fallen.
With such a mountain backing him, Diabolo was very confident in the ultimate victory of the Burning Legion.
Originally in history, the three factions relied entirely on the protagonist's halo and extreme luck to defeat the Burning Legion.
But now, with players who are fully aware of the plot joining the Burning Legion, things are completely different.
Of course, he had no intention of sharing this information with Tichondrius.
