Hmm, so the subculture that's about to tragically end is the peep-other-travellers-books one? Hmm, guess I can do without that one.
Even when I was only reading P-books in public transport, I was not exactly overjoyed if strangers chose to address me over my choice of reading material.
Yes, sometimes I see somebody reading a book that I think is a good one. Do I address them to commend them on it? Ask how they like it? Tell them the punch line? Most often not, as I guess that the fact that they are reading a book that I am also interested in does not mean that they would prefer discussing the book to reading it in peace.
And the only times when I was myself looking at others' books were mainly when I was thinking myself "shit, should have packed a book myself. Stupid me to forget that".