In order for an international flight to work the airline would have to have business class and first class customers. Discount carriers won't work. Businesses aren't going to want to put executives on low cost airlines.
Any airline that launches MCI-Europe likely wouldn't offer first class anyways. DL doesn't have a first class, BA's 788s don't have an FC cabin and most of LH's A330s don't either. Eurowings is hardly a discount carrier. Their A330s onboard product/service are exactly the same as LH minus the first class cabin.
Eurowings own website says they are Lufthansa Groups low cost airline. That is their whole reason for being. Why should anyone think that is incorrect and believe you instead?
Most international carriers have first class. You're singling out a few airplanes that don't.
It’s a lot more than just a few airplanes…
Actually a lot of international carriers don’t offer first class. It’s normally business, premium Econ and economy. There’s some who do offer first, such as Emirates, some British Airways flights and some Lufthansa flights etc, but it’s on a small portion of the long haul fleet in many cases.
There’s no first class on many of Lufthansa’s long haul aircraft, just business and it’s very comparable to the Eurowings Discover long haul business product. Eurowings Discover is Lufthansa’s way to launch new markets at a lower operating cost.