If you blaspheme against the holy spirit (whatever that may entail) but you believe in Christ, the above verse says that you will have everlasting life.
You ignore the essential unity of the Trinity. Jesus and the Holy Spirit are one; to deny the Holy Spirit in ones heart is to disbelieve in Jesus. It is this essential incompatibility which makes forgiveness impossible, because it is a rejection of Jesus' sacrifice, without which our sins cannot be forgiven.
When the Bible was written, the Trinity wasn't really a doctrine according to Bart Ehrman. It came in later, almost a compromise position.
Like most Christian doctrine. It's always interesting to me how people on this forum assume a biblical literalist, scripture-only theology.
Except, the Bible literally says you can speak against "the Son of Man" and be forgiven, and elsewhere "the Son of Man" is pretty clearly meant to refer to Jesus himself.
It is my understanding that blasphemy against the Holy Spirit does not consist in speaking against the Holy Spirit in words, but in the intentional and persistent rejection
of the the forgiveness of God, which is the province of the Holy Spirit. It is persistence in this rejection of salvation that cannot be forgiven, and it will result in the permanent withdrawal of the Holy Spirit from him—whereafter he will not be capable of seeking God's forgiveness. If one confesses one's sins and receives forgiveness, he is not guilty of blaspheming against the Holy Spirit, no matter what he might have said. The sin is unpardonable not because the sacrifice of Christ was inadequate to pardon the sin if one believes in Jesus, but because one who is guilty of the sin will willfully not believe in Jesus and will not seek the forgiveness of God.
ETA: Please note that I don't believe any of this. I just get annoyed when people straw-man religious beliefs. There's quite enough that's ludicrous about religious teaching without distorting what is actually taught.