It Will Be Even Bigger Than The Sea Wolf Class
If the SSN(X) is coming with the requisite armaments and features to outstrip its competition, it wants a larger hull than the Seal Wolf and Virginia versions. 9,100 tons can be borne by the former, although the latter has a size of 7,800 tons.
The Engine Might Rely On Two Types Of Fuel
A vessel that large would require a ton of fuel, as you would expect. An engine that operates on both diesel-electric and nuclear power can come with a new design. There is already a lot of preparation to be undertaken, though.