In this (not my blog) shows a future problem for publishers and one i have hit as quite a few of the books i like have sequels. Iain M Banks has this problem so reading his s/f series from scratch is not going to happen.
Copyright is meant to make authors rewarded. However if one cannot buy/lend the specific series titles (Banks started in the 1980’s) then how is this making his estate rich ? being deceased.
This problem and focus on sequels shows that copyright has lost the plot and publishers would rather not pay authors,