List of albums that will still be popular 50 years from now...

@  rja.  So do I.
The first Chipmunk LP (1959) remains a collector item, and continues to increase in value. The Chipmunks are depicted on the cover as drawn images of Chipmunks, instead of the widely known cartoon characters.
From 1959 to 1961 (first 3 LP's) were depicted as actual images of chipmunks.  
David Seville And The Chipmunks - Let's All Sing With The Chipmunks ‎(LP, Album, Mono, Red) Liberty LRP 3132 1959
Will people still be collecting it in 50 years or listening to it in 50 years, remains to be seen/heard. Most of the people I have played it to really enjoyed it; in fact I have actually seen it bring tears to the eyes of a few. I think it takes them back to a happy time (childhood) 

Early James Taylor
Eva Cassidy, Songbird
Cat Stevens
Early Simon and Garfunkel 
and in case people are not all on anti-depressants...
Leonard Cohen.

Of course we’re only speculating because it’s impossible to
predict but it’s kind of fun.
My feeling is there will be some surprises that would shock many of us.
So yes, I was halfway serious with the Chipmunks.

The Stooges

Other than the Stooges, the Beatles will be one of very few pop bands from their era still being played in 100 years.