The number of people who can live in God's house is not limited. He can accommodate all who come to Him. You don't need to worry.
Many people have been told that Jesus is going to heaven to build homes or mansions for us, but this is not what Jesus is saying. He is going to take His blood and sprinkle it on the altar in heaven so that all who follow Him can have access to the Father.
Jesus went into the Tabernacle in heaven with His blood, preparing the way for us to enter into the presence of God:
Heb. 9:11But when Christ came as high priest of the good things that are now already here, he went through the greater and more perfect tabernacle that is not made with human hands, that is to say, is not a part of this creation. 12 He did not enter by means of the blood of goats and calves; but he entered the Most Holy Place once for all by his own blood, thus obtaining eternal redemption.
He prepared the way. We now can enter into God's presence by the blood of Jesus:
Heb. 10:19Therefore, brothers and sisters, since we have confidence to enter the Most Holy Place by the blood of Jesus, 20 by a new and living way opened for us through the curtain, that is, his body, 21 and since we have a great priest over the house of God, 22 let us draw near to God with a sincere heart and with the full assurance that faith brings, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water.