Is this “Pentecost” just for the original disciples?

In the book of John, Jesus spent a lot of time talking to His disciples about the Holy Spirit just before He was crucified, and He prayed to His Father:

Neither pray I for these alone, but for them also which shall believe on me through their word; John 17:20

Also in the second chapter of Acts, after the Pentecost:

Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. 39 For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.     Acts 2:38-39

And in the eighth chapter of Acts:

Now when the apostles which were at Jerusalem heard that Samaria had received the word of God, they sent unto them Peter and John:  Who, when they were come down, prayed for them, that they might receive the Holy Ghost:  (For as yet he was fallen upon none of them: only they were baptized in the name of the Lord Jesus.)  Then laid they their hands on them, and they received the Holy Ghost.      Acts 8:14-17

For as many as are led by the Spirit of God, they are the sons of God.  For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.  The Spirit itself beareth witness with our spirit, that we are the children of God: Romans 8:14-16

This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh.   Gal 5:16

But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.    Romans 8:9

For through him we both have access by one Spirit unto the Father.  Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God;  And are built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone;  In whom all the building fitly framed together groweth unto an holy temple in the Lord:  In whom ye also are builded together for an habitation of God through the Spirit. Eph 2:18-22