If you think about it, we are all replacement apostles. The use of lots to select Matthias speaks to the work of the Spirit in selecting us for what we need to do. We must also ask did "Joseph called Barsabbas, who was also known as Justus" (Acts 1:23) stop being called just because the lot did not fall in his favor? It matters not because we probably know as much about him as we do about Matthias, which means both men lived out their call to holiness in simple grace and humility. So it is for us. Those of us called to "greatness" must not find pride or pleasure in it; those of us called to "lesser duties" must also find no shame or displeasure in it. It is our job to "become with us a witness to his resurrection.” (ibid 22b)
"I have told you this so that my joy might be in you and your joy might be complete.
This is my commandment: love one another as I love you.
No one has greater love than this, to lay down one's life for one's friends.
You are my friends if you do what I command you.
I no longer call you slaves, because a slave does not know what his master is doing.
I have called you friends, because I have told you everything I have heard from my Father. It was not you who chose me, but I who chose you and appointed you to go and bear fruit that will remain, so that whatever you ask the Father in my name he may give you.
This I command you: love one another."
-- John 15:9-17