In this section, Fee comments on 2 Corinthians 5:13, "Now the one who prepared us for this very purpose is God, who gave us the Spirit as a down payment." (NET)
Again, Fee points out that the "down payment" language is eschatological. The Spirit is evidence that we are living in the "latter days," and it is a foretaste of what is to come.
And here is where our sentence fits in. Whether we die or are transformed, God has fashioned us for this future bodily existence, in which the present mortal body is swallowed up by life. The clearest evidence of for this is the gift of the Spirit, which functions for us as God' down payment that we shall indeed inherit the very thing God has fashioned us for, namely, a new form of bodily existence in a pneumatikon soma ('Spiritual body'; 1 Cor 15:44) or soma tes doxes (a 'body of glory'; Phil 3:21).
Two things need to be emphasized about the second appearance of 'down payment' imagery in the letter: First, as we have already noted on 1:22, this is a case where the Spirit serves as the evidence for Paul of our essentially eschatological existence. We are destined for a glorious future, which is guaranteed precisely because the down payment of that future, the Spirit himself, is already our present possession. In giving us his Spirit, God has guaranteed our future. Thus, we live in the present, 'already' but 'not yet.' (326, Greek transliteration mine)