In a much different (perfect) world, yes. Once sin (corruption) entered the world, they still had extraordinary long life (900+ years) because the decay which brings about death was new to the world. The forces which work against us (to age us and wear us down) were just beginning and Adam and Eve were not plagued with any genetic mutations or disease which would have brought about their demise - as we see today. So it took longer for them to die. Their bodies were perfect and yes, meant to last forever! As time has worn on, we see the full effect of the corruption that entered the world in Eden. If you have ever studied the laws of thermodynamics, you see the picture scientifically! It is a scientific law that the earth has been wound up and BEGUN at a specific point and has been unwinding (wearing down) ever since, just like the Bible says it was. Everything in the universe is slowing down, wearing out and decaying, not the other way around (as evolution teaches.)
The perfect world of Eden IS how God intended it to be. What we experience now is a result of man's choice NOT to do things God's way. We are fortunate, however, that He still gives a second chance to those who want it.