I found a village with NO farmers and I also noticed too many librarians so I thought "they will convert occupations after awhile".

after a few minecraft days nothing changed, no farmers still!

you can prove me right or wrong by...
1. locate a village
2. try to find any villager with a "farmer" skin
3A. if you do then its on my PC only
3B. if you don't then you might notice lots of librarians