Then you didn't get what I have intended to say, There are 2256 private keys. There are 2160 legacy addresses calculated from those keys by applying RIPEMD-160 to SHA-256 hash of those keys. It means at the end we have collision as only 2160 legacy addresses will correspond to the whole set of 2256 private keys. Roughly each address can be accessible through the set of 296 keys.
Ah... sorry,
now I get what you mean. Yes, that sounds about right.
To generate all the possible addresses (assuming you never generated the same address twice), it would require you to continue generating addresses for another:
(1.27 X 1028 seconds to generate ALL addresses) / (4.35 X 1017 seconds in the universe) = 29,195,402,299 entire universes worth of time.
Let's not forget though that assuming Moore's Law applies to this hypothetical technology we'd only have about 70 years until computation time will be reduced to a
single universe worth of time.
Just sayin'
(70 years of computation power doubling every two years => 2^35 = 34,359,738,368 times the computation power you started with. Yes I'm aware that
technically that's neither what Moore's Law states nor how any of this works.)