He would be hurled away to die in a far land. He would not even have an ordinary grave in Jerusalem, much less a royal one. All the honour attached to his position would be taken away from him.
Nothing is known about Shebna’s death. It is, however, known that he lost his position as steward of the palace as Isaiah prophesied: In Isaiah 36:1–22 we read that Eliakim was over the household.
17 Behold, the LORD will hurl you away violently, O you strong man. He will seize firm hold on you