Answer:
He is wishing he could become like the nightingale.
Step-by-step explanation:
In the stanza, the speaker is telling about the death and how is he calling for it. He thinks that in death "Now more than ever seems it rich to die". The death brings relief and the speaker is calling her name with love.
In the last two lines of the stanza, there is a will of the speaker who would sing a song but he can't. He imagines the disappearance of the physical world and sees himself as dead as the earth over which the nightingale sings. He wants to sing like a nightingale but " Still wouldst thou sing, and I have ears in vain— To thy high requiem become a sod." Metaphorically his ears became a sod and he can not hear a song. Even though he wants to sing, his wish can not be pleased. He wants to be like a nightingale.