Melbourne and Perth have been running under 18s sides in the premier NSW comp (SG Ball cup) in recent years. Perth do better than Melbourne, due to the high number of NSW and Qld ex-pats living in rapidly growing Perth.
The Melbourne teams are largely members of the Kiwi and Polynesian communities, who don't take to AFL so much.

In 21 years the Storm have played in 9 Grand Finals, won 5 titles, 2 stripped for cheating, are the #5 best supported NRL side and as of their 2019 Squad as listed on Wikipedia, not one of their players was born in Victoria, but plenty were from NSW/Qland, NZ, Fiji and PNG.

None of this seems to bother the fans of other NRL clubs, nor thew TV companies, the NRL/ARL or anyone else, but they were protected from relegation, which begs the question that if money bill and whomever Argyle sneaks under the cap for 2020 don't stop them from going straight back down, will the SL expand or will they be allowed to slip back down the ladder?

The other scenario is that Argyle rides roughshod over the cap in pursuit of glory....how do the SL chairmen handle that?

Just wait until TW go hard after a star/marquee player from one of the top 5 SL Clubs & get him, see the reaction of SL Club owners & fans then.

Problem is they have 2 marquee players already and a snide Union convert.......as I say, If argyle says "sod it' and buys the comp, what can the current SL sides do?
He's spent £10,000,000 so far.......that's more than SL sides do in a year. If he want's it....well, it's his!