Well, in the Marine Corps and Navy lexicon LPD, LHD and so on are not neither mutually exclusive nor optional.

All LHDs have like their main reason to provide vertical lift, and command and controls functions for the amphibious assualt.

All LPD should provide core logistic support, second wave anphibious assault, and with LPD-17 four ships out of eight will provide command and control functions as well, that’s the reason behind the four Harpers Ferry logistic LSDs (being four San Antonio class ships deprived in logistic capabilities to make room for the C3I centre, they put an Harper Ferry beside a C3I-augmented San Antonio).

First assault is demanded to an LHD and a Widbey Island class LSD, sencond wave and sustainment is mostly done by LPDs, plus assets from an LHD, optionally an Harper Ferry class, and other ships.

About LHA6: they are purchasing lots of F-35B, they will need some good ferry to move them on theatre, and will need some technical facilities, but they are not giving up the LHD or LHA main role, i.e. the air assault.