The Belair name is well established in the Swiss market since the airline has been active in the charter market for decades (first as Balair, then as Belair). I don't know if it makes sense to change it. Nevertheless, all ZRH based AB planes are in AB livery and carry a sticker next to the door saying "operated by Belair". AB has already reduced the 4T brand appearance to a minimum.

The Belair operating certificate is necessary for flights to destinations outside the European Union, where the EU open skies area does not apply. All flights from ZRH to airports in the EU (Greece, Spain, Italy, etc.) carry the AB code (even if in theory operated by 4T planes in AB livery ). Flights to destinations such as Pristina, Sharm-el-Sheikh, Hurgada, Antalya carry the 4T code since the bilaterals between Switzerland and these countries require a Swiss company to operate the flights. These flights, too, are operated by the same planes in AB livery.

I believe an Austrian subbrand such as NIKI to be necessary for those ex-VIE flights bound for points outside the open skies area.

Well, I think separate companies are OK even when sharing brand. And I think we were talking about brand, not company (after all, AB doesn't own all 100% of NIKI)

Absolutely, they may become all airberlin keeping Belair and Niki as legal entities to enjoy those flight rights connected to their "nationality" when this is necessary. In fact here in ZRH Belair only appears on the schedules but the customer experience is all AB, from check-in to AB branded plane to AB onboard service, etc.

sorry I would have more info on niki on hand, however -
1) do they have business class section on the plane?
2) do they have airport lounges as a requirement to satisfy (1) above?

if they don't I just dont understand what (except priority boarding and baggage) is left there in terms of OW benefits they can offer )
AX

There is lounge access in the stations they have an agreement with a third party lounge (or AB or another OW lounge).

Agree that there's no Business Class, but catering is somewhere between Economy and Business (free sandwich of substantial size, usually choice of two options) ... clearly superior to buy on board and BA's bird seed ...

No only Eco whit C Food/ Snacks Yes = AB -> OW Lounge