(Paraphrasing)This is all about about what Austal, INCAT and Dereckor and Nichols Brothers will be offering the US for the JSV, and potentially what could come out of the development.
Assuming they get to it first, once the US get knees-deep into this sort of development, it is the time that the RAN (and others) can scavenge on some of the development process.
Initially, the WPC looks nice, and has some shortfalls. However, once they are under construction (and not withstanding the goal posts being moved, different committees start hammering around with the usual malleable->rigid->malleable budgetary and capability requirements) lessons get learned.
Some of these lessons will potentially start to answer some of the discharge and landing flexibility questions, and some (such as the long term crew on board) issue would possibly be a 'gripe' that is worked out later if it doesn't come to light at construction and sea trials. Even if Uncle Sam doesn't ge to learn from them, or even is not bothered by them, there is still the likelihood of the builders themselves offering the option as a sweetner to the deal to the next buyer, or that the RAN will see the issues and adjust their capability requirements to fit.
This has not been the case in the past for a lot of countries from purchasing a lot of hardware, but recently there has been a huge amount of corporate intelligence being generated given the current climate.
But in the long run, the shipbuilders aren't going to roll up to the bidding with a completely immobile design philosophy. On the "build it and they will come" marketing values, you need to have a marketable product; to have a marketable product it has to do what the customers need. The RAN just need to make sure they explicitly state all requirements. However as an interim answer, the modular design is supposed to make internal retrofitting easier in some respects*.
(*actual results may vary)
----
@Alexsa:
Further to what AGRA has posted, the type of capability it offers is perfect for us.
Distance wise, it just so happens that the vicinity of 5,000nm-7,000nm at somewhere between best speed and best economy is a pretty nice figure for the ADF (notwithstanding certification values).
With that range, we can go:
-To the Gulf from FBW;
-Anywhere up to Japan from FBE (further from Darwin), or;
-Do a one-stop in Hawaii and make it to US East Coast (or South America) with a reasonable reserve.
This would let us reach most places on the globe we would be reasonably required to attend. Africa, Europe and the continental Americas East Coast (in the case of the Panama and Suez canals being removed from the equation).
This is not taking into account the potential for further technological, development and design improvements to increase performance in the intervening time frame. I suspect by the time we are to replace the Tobruk we'll have a slightly better variant available to us, plus additional bidders from the other builders.
--
Of course, the real issue we people on the ground have at the moment is that we can't see into the future to what the requirements will be.
Certainly I'm not as worried about the issues of diminished capacity over a larger sealift ship - platforms such as C-17 are likely to be cited as a supplement, regardless of the inflexibility of the requirement of an airfield, mainly because that was the rationale for purchasing them.
Generally the idea of an amphibious operation may require speed over numbers in a lot of cases, and it is a
huge humanitarian winner for responding to disasters and the like. You can put a floating hospital, secure troops, supplies and heavy equipment ashore faster than just about anything short of a large airlift, and to anywhere that there is sufficient channel clearance instead of relying on airfields.
I'm not bashing the idea of a larger sealift ship, as they do have their place, but it is just as likely that if another heavy sea lift vessel is requested that the answer will be in the form of the questions: "Then why do we have LHD's? Aren't they for moving large numbers of troops and vehicles around?", as the distinction may not be as obvious to those who write the cheques.
The flexibility and speed of a fast JHSV-style asset makes:
The Army happy (they hate being cooped up on ships),
The Navy happy (as they get the cargo there and back quicker) and
The end-customer a whole lot happier (either the CADF in the case of combat, or the recipient country in humanitarian/support operations)
: 
