"ALL things are delivered to me of my Father..."
"The Father loveth the Son, and hath given all things into his hands."
"Hath in THESE last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds."
Did you catch everything in that last verse? The writer of Hebrews knew first off that believers were living "in these last days" as in the end of the old covenant, the end of Jerusalem and the Temple. We also learn that God has spoken to us by his Son Jesus who in turn reveals God to us. Jesus is "heir of all things" as well and the Creator of all things!
God has given us countless verses to assure believers and to show unbelievers even that he gave full authority to his only begotten Son, Jesus the Christ. Jesus tells us this on several occasions. This is something that has already been established too! There is no time in the future where everything is going to be given to Jesus. Just look at John 17:1b-2 where Jesus speaks about himself in the third person (just like God did in the Old Testament):
"Father, the hour is come; glorify thy Son, that thy Son also may glorify thee: As thou HAST GIVEN him power over all flesh, that he should give eternal life to as many as thou hast given him."
See what I mean by Jesus talking about himself in the third person? He does it all the time. In verse 2 he says God HAD given him power (authority) over all flesh. Look at Hebrews 2:8 for another example:
"Thou hast put all things in subjection under his feet. For in that he put all in subjection under him, he left nothing that is not put under him." So again we see that Jesus HAS full authority over everything, on earth and in heaven. He is the King of kings, the Lord of lords and Prince of princes!
The Holy Ghost testifies of Jesus and he tells us through the Bible that Jesus has all authority and that even the angels worship him (Hebrews 1:6).