Geez, if White and 22 were enough to do the deal, I'd have thought it would have been done a week ago.
With the Suns and Lions effectively out of the race, it puts Adelaide in a much weaker position re PSD. The only legitimate contenders for Tippett's signature would be GWS and maybe Carlton, neither of which are certain to be able to meet his salary demands. GWS have enough solid prospects coming through as well, and recruiting Tippett would probably bump Izzie to the ressies, which isn't a good look. Once their cap shrinks, they won't want to be accommodating Tippett's hefty contract, even if they can now. Tippett doesn't want to go to Victoria, so Carlton probably wouldn't take the risk.
Furthermore, interest in White has probably increased since Giles re-signed with GWS. He's probably a slightly more attractive option now.
Finally, it wouldn't surprise me if a large portion of last week was spent with White and 22 on the table, and Adelaide saying, "let's each go scout out some clubs and see if we can get a third party in on this". Nothing doing, so now Adelaide are resigned to the original offer.
This is all just speculation, of course. I wouldn't dream of assuming Faith's mantle as resident BigFooty psychic.