I will just reiterate what others have said. Regardless of your future decisions you should get your citizenship. Why?
cost of applications will only increase.
goalposts in the future may change...afterall you used to only have been here 2 years as a PR.
the costs already incurred emoyionally and financially to relocate here and stay the amount of time you already have.
it is available to you and there are a lot of people who wou;d give their right arm for (left for lefties :) ) what you already have.
sometimes you dont really appreciate what you have until it is taken away.
If you can afford it go back for a visit. My husband went back after 15 years for a holiday and came back stating we had been right to bring our children here and he was glad his kids didn't have to grow up in that %%%$$$#### place he was from even though he loves Liverpool like all liverpudlians. It had changed far too much, he had seen and tried different things and although it was nice to catch up with people, they really hadn't changed that much and the area he grew up in had changed or else he now viewed it through different eyes.
Some people never settle fully anywhere. You may end up with a foot in each country, so never fully Australian and never fully English again (insert which ever country you may be from). Just think of yourself as a global citizen and the world is yours. Just get the right to come and go from here to keep your options open.