Maybe they take 50% ownership share of Nix now (and pay for it), with an agreement that if the Nix in 2 years time are not granted a licence extension (by the FFA or Independent A League - whoever is running the show) - then SWS buy the remaining 50% of the licence (if licence is indeed transferable). Sort of like a 2 year option, that is used a bit in larger property deals.
However if Nix survive beyond 2 years, then they just stay on as 50% owners, or sell 50% back to Welnix, or sell 50% to someone else - possibly at a profit if Nix are performing well, and/or an Independent run A League is actually making money. With this 2nd scenario, SWS would then have to try secure their own new licence, in a new wave of A League expansion.
The motivation for Welnix in a part sale like this, is of course they at least they get some of their big dollars investment back now, when at the moment is a real risk in 2 years they lose the lot, ie get not a cent back. After 6-7 years no prospects have surfaced in NZ, so they have looked to Oz. At same time they have 2 years to try turns things around on & off the field, whilst still retaining most of the games in Wellington.
Of course this is all, complete guesswork and speculation - but I see some sort of deal like the above being struck - if a deal is struck at all.
I love your thinking, Coochiee. A scenario I could definitely live with. Now, if the Nix could just quickly, and loudly, announce a Wellington based coach, for next season's (predominantly) Wellington based Nix season...