If Adam had not sinned would he ever have died?

No, he would have lived for ever:-

Gen 3:17-19 MKJV And to Adam He said, Because you have listened to the voice of your wife and have eaten of the tree, of which I commanded you, saying, You shall not eat of it! The ground is cursed for your sake. In pain shall you eat of it all the days of your life. [v.18] It shall also bring forth thorns and thistles to you, and you shall eat the herb of the field. [v. 19] In the sweat of your face you shall eat bread until you return to the ground, for out of it you were taken. For dust you are, and to dust you shall return.[ie die]

Gen 5:5 MKJV And all the days that Adam lived were nine hundred and thirty years. And he died.

1Co 15:21-26 MKJV For since death is through man[ie Adam], the resurrection of the dead also is through a Man [ie Christ]. [v. 22] For as in Adam all die, even so in Christ all will be made alive. [v. 23] But each in his own order: Christ the first-fruit, and afterward they who are Christ's at His coming; [v. 24] then is the end, when He delivers the kingdom to God, even the Father; when He makes to cease all rule and all authority and power. [v. 25] for it is right for Him to reign until He has put all the enemies under His feet. [v. 26] The last enemy made to cease is death.

However, because Adam sinned, he brought sin into the world. Think of 'sin' as a gene in a person's DNA that is automatically passed on to all his descendants. The only way the penalty of sin can be removed is by accepting Jesus Christ as Lord and Saviour, and then you will live for ever.