There are a lot of question so I will settle on the one in the title.  

How many years will an current aluminum frame last of a touring bike?  

Depends:

 - Don't know what aluminum frame   
Construction is a larger factor than material 
 - Don't know the use   
Use is a larger factor than material
 - Don't know how you are going to care for the bike   
Care/maintenance is larger factor than material 

Aluminum has not changed in the 10 years 

All we know is your last aluminum, high quality, strong frame bike lasted about 10 years   

The best guess is your next aluminum, high quality, strong frame will also last 10 years   
Really that is the best guess  

That is as vague as how long will a current pair of sneakers last me?   
And the best guess for how long my next pair of sneakers will last is how long did my last pair last.  

Aluminum fatigues and steel does not fatigue.  

If you are discounting steel because it will rust then you are not caring for the bike properly.  A properly maintained and stored steel bike should not rust.  And for sure it should not rust out in your life time.   You stated bikes from you fathers era lasted 40-50 years - pretty sure they were steel bikes.

If you want fatigue free and rust free then get titanium.