After reaching Qantas Platinum One status, what's next?

I am about to hit the 3,600 status credits to renew my P1. I am at the 6 month point in my annual cycle. From a bit of reading, the benefits beyond 3,600 status credits are not really blowing me away - either 75,000  points at 5,000 status credits / or 100,000 points at 7,000 SC's(and I'm already drowning in points). I also believe I must only fly on QF tickets to get to those levels (which I probably wont hit as Qantas doenst fly to enough places I go to). I am also Lifetime gold, so there is nothing to shoot for there

If you mainly travel to London although it's a OneWorld airline, BA could be a good choice. BA has Lifetime Gold (Gold on BA is similar to Platinum on QANTAS and is Oneworld Emerald). If you fly enough for Lifetime Gold on BA to be realistic it could be well worth chasing.

you could go emirates, spend over 50k a year with them (which by many reports is what it takes) and get invited to join their invitation only program (IO) which gets you access to the chairmans lounge

I would suggest looking at a Star Alliance Airline - SIA and their Kris Flyer programme is good/accessible for AU resident - plus they have the route network and world class product to support your destinations. This will also mean you will accrue status in the 2 major alliances therefore your travels will allow you a lot more freedom of routes/airlines to choose from. Wish i had your problem!

I'd suggest going to SQ which also gives you status with VA as well as across the Star Alliance.  I'm pretty sure SQ would probably status match almost immediately

Why do you need to do anything? Keep accumulating the points on QF and then you can just fly on points on any OneWorld airline. Swapping across to another program means you start from 0... 0 points, 0 status. I stuck to one program and now have well over 1.5 million points and I book all my overseas holidays in Business Class and only have to pay taxes.

I agree with getting in with the star alliance program, and id suggest either Singapore Airlines or Etihad. 

Definitely Star Alliance using SQ

Private Jet?