Oh hey that's me! All I did was upload a snippet of a TV show ahaha! Thanks...
I have thought about this a lot too and there are really three possibilities I come down to. The first is that Luna Park still exists today, but it's very different to what we know it as. The pop-art aesthetic would still exist and the classic rides such as Big Dipper, River Caves and Coney Island may exist. Back in 1979, the owners could have demolished anything they wanted (of course, with public disapproval, but they would probably be allowed to get rid of Coney Island, for example). There were no heritage laws stopping them. Who knows what the owners could've added or removed!
The second is the park had another bad accident that causes it to close for good. The owners didn't really give Luna Park the attention it deserved after Ted Hopkins left, and through what I've seen, the place looked run down in the late 70s, even with Martin Sharp's art team. In April of 1979 two trains on Big Dipper collided, and the park hadn't been following fire safety standards. A worse accident could've happened, closing the place for good.
The third is just that the park loses attendance and withers away. It's a boring scenario but this shit happens. That was the fate of the original Luna Park in the 40s.
In conclusion, Luna Park would be a different place and might not even exist, but there are too many possibilities and I won't be able to even think of them, and you just spend too long reading me rambling on about an amusement park ahaha.