So far we have the B5N2, Tiger I, P-51D redux and Me163 coming in 1.11.
The only one of these that will see a lot of use in the MA is the P-51D, which isn't really a new aircraft (though it does look gorgeous).
The B5N2 is a death trap in scenarios, in the MA it would be absolutely helpless. As in the case of all early war units, it will see basically no use in the MA. The B5N2 will be somewhat useful in scenarios and CT setups.
The Tiger I will be perked. As with all perk units it will see essenetially no use in the MA. The Tiger I will be useful in scenarios and CT setups to give the Germans the edge they had in tank quality by giving the US / UK the PnZ IV H and the Germans both the PnZ IV H and Tiger I.
The Me163 will only be positioned (as I understand it) near the HQ to ward off bomber attacks. As bomber attacks hardly ever occur, and are less than a threat when they do, the Me163 will mostly sit in the hanger waiting for a threat that simply isn't present in AH. The Me163 is essentially useless in scenarios and the CT.
The Ki.84-I would be tremendously useful in both the MA and in scenarios and the CT. I cannont think of any other aicraft that can make that claim. The Ki.84 isn't good enough to warrant perking and yet it is very good which means that it will get used in the MA. In the context of scenarios and CT setups the Ki.84 would be useful as a very common late war Japanese fighter. It served for more than a year of wartime (something the Fw190D-9 and Tempest Mk V cannot claim) and 3,514 were built, the third highest total of any Japanese fighter. It was not a rare production wonder bird like the N1K2-J.
IMO, the Ki.84-I would be, in terms of player hours spent using it, one of the, if not the, best investments in effort HTC could make.