Paul ends his letter with a repeated wish for their prayers for him as he heads to Jerusalem and his expectation that he will one day come personally to Rome, on his way to minister in Spain. We read back in Acts that his visit to Rome was fulfilled but from a different context.
As for his ending message…it contains this reiteration of doing all for the Glory of God.
Q. 1. What is the chief end of man?
A. Man’s chief end is to glorify God, and to enjoy him forever.
Rom 15:5 Now the God of patience and consolation grant you to be likeminded one toward another according to Christ Jesus:
Rom 15:6 That ye may with one mind and one mouth glorify God, even the Father of our Lord Jesus Christ.
Rom 15:7 Wherefore receive ye one another, as Christ also received us to the glory of God.
Rom 15:8 Now I say that Jesus Christ was a minister of the circumcision for the truth of God, to confirm the promises made unto the fathers:
Rom 15:9 And that the Gentiles might glorify God for his mercy; as it is written, For this cause I will confess to thee among the Gentiles, and sing unto thy name.
Rom 15:10 And again he saith, Rejoice, ye Gentiles, with his people.
Rom 15:11 And again, Praise the Lord, all ye Gentiles; and laud him, all ye people.
Rom 15:12 And again, Esaias saith, There shall be a root of Jesse, and he that shall rise to reign over the Gentiles; in him shall the Gentiles trust.
Rom 15:13 Now the God of hope fill you with all joy and peace in believing, that ye may abound in hope, through the power of the Holy Ghost.