i think we have to break it down in that the politics of this are just plain nasty. It will be a major effort to just stop paying welfare to those on avg + incomes as we currently do.
I think that has to come first so that we continue to have the capacity to provide a welfare safety net.
Once that's achieve, then the tricky issue of high EMTRs can be tackled. I honestly don't believe they can be done at the same time, unless we moved into a double rainbow and unicorns for all kind of world where Government and opposition constructively work together.
IMHO, it'll take a recession to get a reduction in middle / upper class welfare.