My missus us a better WK than Buttler. Those 3 yesterday were flukes. Foakes ton,

[Burney]

How many of our batsmen have performed well in Oz and are still in reasonable form?

I'm not sure where the optimism comes from. Warner and Smith are fully over cheatgate and we're going to need to take more than 1-125 from spin per game.

We are going to get absolutely battered.

Well Root averages 48 over there, Stokes averages nearly 40 and has made a ton there and is now 10 times the batsman he was then. The others haven't really played there, but we now have two very, very promising young middle order batsmen and an opening pair who, while they have their faults, are capable of making 50 partnerships with a consistency we haven't seen since Cook and Strauss.
Be as miserable as you like, but there are grounds for optimism.