That's nothing new. You can preorder movie tie-in merchandise like soundtracks and books long before they even get printed or pressed to disc.
I know, but talk about taking a leap of faith. This is Marc Streitenfeld we are talking about, here.
I presume, even though he has been given his walking papers, much of the soundtrack will still be his work (although, I could be wrong, and maybe Ridley is throwing it all out, and starting over).