I guess pretty much the same that happened when an European airline ordered a DC-9 or a MD-83
(or when they order a 737-800, for that matter). Firstly, it is flown almost empty , almost no seats and so on, and only a few guests , if any fly the delivey flight (Top airline officials and so on), sometimes extra deposits are used, and most important, special flight paths are used, I reckon from US to Europe is usually via Canada and Greenland, IIRC .
For very long oversea flights special fuel tanks can be installed inside the cabin. But I don't think that this can technically be done for every model.
If a long flight has to be made between two airports separated by water, desert, jungle or whatever and there's no suitable airport en route for a fuel stop, Airbus would probably do with its hypothetical QANTAS' A318 what Boeing did for Hawaiian Airlines' B717 (nee MD-95).
Get a map of the Pacific Ocean, then draw the range of the B717 (roughly 2000 nm) starting from the West Coast.
See what I mean ?
Boeing installs extra fuel tanks in the cabin, connected to the fuel lines running between the wings.
Do ETOPS rules apply even though it's a ferry flight???
As far as I know they do, however there may be exceptions granted, such as when Ken Borek Air flew a Twin Otter from Calgary to Antarctica to rescue a Doctor who was seriously ill, and could not be airlifted by any other aircraft.
Also I would assume the Airlines insurance carriers might have some problems with flying outside the rules.
Could be wrong on this one, but AFAIK ETOPS rules only apply to commercial operations. And are optional for the others.
Private operators don't have to follow these rules although it is highly recommended to do so. I guess you could ask for ETOPS approval even though you are not a commercial operator.
If you are privately operating a twin you are limited to 60 min... Unless you ask for more and thus demonstrate your flight ops, training and maintenance departments are compliant with the regulations.
ETOPS approval "by default" is 60 min. for start-up airlines. As times goes by they get more, provided they have engine reliability statistics in their favor and conducted extended reliability trials (especially on engines).