Will you still be doing travel on United? The miles will all merge into a dividend miles account that can be redeemed for travel on any *A member, including Asia or Aus. Right now, 2 First class tickets to Asia are 240K total miles, and 300K to Aus.
I recommend keeping the miles and letting them build up. If you fly the new US or United, you can earn miles on what will be your new Dividend Miles account.