The general thought is that the unofficial line of songs goes as such:

Space Oddity
Ashes to Ashes
Time Will Crawl
Hallo Space Boy

Does "Never Get Old" come next? Lets look at the lyrics:

In reply to:

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Better take care
I think I better go, I better get a room, better take care of me
Again and again
I think about this and i think about personal history
Better take care
I breathe so deep when the movie gets real when the stars turn around

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Major Tom was struggling for an answer and direction after Hallo Space Boy

In reply to:

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Again and again
He looks me in the eye and he says he’s got his mind on a count-down 3-2-1

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Count-down is an obvious gimme

In reply to:

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Forever
I’m screaming i’m gonna be living on till the end time
Forever
The sky splits open to a dull red skull and my head hangs low cause i’ts all over now

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Refrence to Space, and another throw from Time Will Crawl

In reply to:

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There’s never gonna be enough money
There’s never gonna be enough drugs
And i’m never ever gonna get old
There’s never gonna be enough bullets
There’s never gonna be enough sex
And i’m never ever gonna get old
So i’m never ever gonna get high
And i’m never ever gonna get low
And i’m never ever gonna get old

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In Ashes to Ashes, Major Tom was remarking that he has no money or hair.. here he seems to get past this.

In reply to:

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Better take care
The moon flows until the end of the world because of you
Again and again
And i’m awake to an age of light and i’m living it because of you
Better take care
Looking at the future, soud as a rock, because of you
Again and again
I wanna be a here then i wanna be there, living just like you living just like me
Forever
Putting on my gloves and i bury my bones in the Marshland
Forever
Think about my soul but i don’t need a thing just the ring of the bell in the pure clean air

Now i’m running down the street of life
And i’m never gonna let you die
And i’m never ever gonna get old
And i’m never ever gonna get…
And i’m never ever gonna get…

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I think It's pretty obvious from here on, with refrences to space and fate. Although I don't claim to be able to correctly interpret any Bowie lyrics better than anything else, I think it's pretty clear that Space Oddity is about a bad trip, and never comming down. Ashes to Ashes is a reflection on this, perhaps a moment of clarity, that alcoholics sometimes claim to have ("I heard a rumour from ground control/oh no don't say it's true/they got a message from the action man"). Time Will Crawl is a continuation of this, and further plunges into the drug-induced lifestyle. Hallo Space Boy is where he perhaps hits rock bottom, and is confused, left behind. Never Get Old, as Reality, is a comming to terms and equalization of his life. Here, Major Tom is able to find balance, realizing he can't have it all, but he can keep on partying if he keeps his head on the ground.

Joethelion
And it was cold and it rained so I felt like an actor