The Lifespan of an LP?

When you have a lot of albums it is never a problem. We get bored playing the same record over and over. Say you average listening to two records a day. That is just over 700 records a year. Many of us have 5,000 plus records. A record might get played once every six years. Records that you really like might get played a total of 10 times. With a good system and the best care a record will last indefinitely. The problem is most people do not take the best care of records. I personally do not buy used records. If I was at an estate sale I would consider buying a single large collection. The bigger the collection the less the records were played. Then you sell off the records you don't like.
Under the best conditions a record can probably be played 50 times or more. Time is not the issue. It is the number of plays. Also remember old records were played with either spherical or elliptical styli. Our modern fine line styli produce less record wear. 

I bought my first album in 1967 and like many albums I own from the 60s, 70s and 80s, played the hell out of it. I always took good care of my vinyl. But the grooves on my favorite albums (many of which have been played over 100 times) appear noticeably worn.
Up until the 1990s, I used the likes of a Shure V15Type lll with elliptical stylus at 1 gram in a modest system. Starting in around the year 1995, I started to get into high end audio with much more expensive and revealing gear. I switched to cartridges like the Dynavector XV1-s and the Atlas line. To this day, all of my albums sound as good as new and almost always sound better than reissues off of the master tape. Is it because a line contact stylus hits a different point in the groove and only the top of the groove is actually compromised? Is the top of the groove compromised merely because it looks worn? I don’t know--but in any event, all of my records sound great today and will sound great long after I’m gone.

It's been a while for me, but the first three plays were the best. 

The ARSC Guide to Audio Preservation, 2015 (https://www.clir.org/wp-content/uploads/sites/6/pub164.pdf) commissioned for and sponsored by the National Recording Preservation Board of the Library of Congress, states: “Vinyl discs are the most stable physical sound recording format developed to date; they can last 100 years in a controlled environment.”  History will probably show >100 years.

The RCA record composition developed (early 1970's) for quadrasonic play with a Shibata stylus (RCA Engineer Magazine, 1976, Issue
02-03, Development of Compound for Quadradiscs, by G.A. Bogantz S.K. Khanna 1976-02-03.pdf (worldradiohistory.com)) at 1.5 gram after 100 plays showed little or no wear. They did show clean-narrow trenching with a Conical stylus at 4.5 grams after 100 plays, but a Shibata or equivalent stylus shape would bridge the trench and playback with full fidelity. 

We should hope that current record compositions follow what RCA developed which is open source info they detailed in their patent - RCA Patent 3,960,790, June 1, 1976, DISC RECORD AND METHOD OF COMPOUNDING DISC RECORD COMPOSITION  1498409551006799538-03960790 (storage.googleapis.com)

That’s what she said, Russ.