I can't vouch for the accuracy of this, but here's what I found. Apparently, the song was also recorded by Elvis Presley.
-Joe-

A Hundred Years From Now
(Lester Flatt)

Well a hundred years from now I won't be crying
A hundred years from now I won't be blue
And my heart will have forgotton she broke every vow
I won't care a hundred years from now

Oh, it seems like yesterday you told me
You couldn't live without my love somehow
Now that you're with another it breaks my heart
Somehow I won't care a hundred years from now

* Refrain
Now do you recall the night sweetheart you promised
Another's kiss you never would allow
That's all in the past dear it didn't seem to last
I won't care a hundred years from now

* Refrain

from recording by TONY RICE - The Bluegrass Album Volume 3

Source: http://www.bluegrassnet.com/tgbs/A/A_hundred_years_from_now.html

The Harry fox Agency Website, songfile.com, lists a number of songs with the title "A Hundred Years from Now." I found one recording with that title in my library - the Gram Parsons song recorded by the Byrds on Sweethearts of the Rodeo - the Gram Parsons song isn't it, and as far as I can tell, Harry Fox doesn't have a song with that title attributed to Flatt. Lester Flatt did record this song under the title I Won't Care (A Hundred Years from Now)