There were different types of entails and settlements. In canon P&P, there was an entail completely excluding females from inheriting Longbourn. But there were also entails that followed the custom of primogeniture to some extent by giving a son, even if he was the youngest sibling, the priority in inheritance, but which allowed the eldest daughter to inherit if there was no son.
I sometimes wonder about the altered dynamics if, instead of completely excluding females, Longbourn was entailed so as to make Jane, as eldest daughter, the heiress if there was no son. How would the dynamics of relationships be altered in such an AU? Would Mrs Bennet be more anxious only for her younger daughters to marry well since Jane was already well-provided for as an heiress? Would Bingley's sisters be eager for him to marry Jane so that he could have an estate without having to purchase one? Would they make their eagerness so obvious that Eliz became suspicious and decided that Bingley was not really in love with Jane, and perhaps arranging for her to visit the Gardiners to get her away from Bingley? (Eliz and Darcy in role reversal here!) What do others think of the possibilities?
I sometimes wonder about the altered dynamics if, instead of completely excluding females, Longbourn was entailed so as to make Jane, as eldest daughter, the heiress if there was no son. How would the dynamics of relationships be altered in such an AU? Would Mrs Bennet be more anxious only for her younger daughters to marry well since Jane was already well-provided for as an heiress? Would Bingley's sisters be eager for him to marry Jane so that he could have an estate without having to purchase one? Would they make their eagerness so obvious that Eliz became suspicious and decided that Bingley was not really in love with Jane, and perhaps arranging for her to visit the Gardiners to get her away from Bingley? (Eliz and Darcy in role reversal here!) What do others think of the possibilities?