It probably does not matter which party holds power - small GA is rooted. Avgas will go, not because of the Greens, but simply because as the demand diminishes it won't be worth refining, or if someone does bother it will be 5 times the cost of jet fuel.
There is not enough votes in the entire industry to make any difference to the pollies, so all the lobbying in the world won't save it.
The only small GA segment likely to survive is the training industry, but that will have to be underwritten by the end consumers - ie airlines and wealthy individuals.