It would if baseball had taken over the local club competition
That’s a perfect analogy actually and something I was going to use. There would be literally thousands more people watching MLB in Australia than there would be watching the Sheffield Shield - I think there was a stat where the MLB is one of the most popular competitions.
Yet after all that how many people play baseball? How many people would watch the domestic baseball competition? How many people would watch the national baseball team (who are nicknamed the Thunder btw). Not many. In fact international baseball as a whole (at least from our perspective) wouldn’t be anywhere near as significant as international cricket.
That’s the thing: the comparison isn’t between the domestic competitions. You have to work out what draws people (athletes/crowd) to the other sport. For example for people to care about baseball outside of MLB and take over cricket you actually have to demystify the whole baggy green thing, the cultural thing that Australians have with cricket.
Same with RL and Union. In order for RL to take over Union in that country you have to make the All Blacks and the cultural affinity they have with that team irrelevant. That’s not going to happen by just plonking a side there. It would require mountains of investment over a long term as well as good fortune i.e their game dying in the ass.