If it happens, Spurs are ed. They were still ed by OKC being better so it doesn't really change their issue. Spurs ceiling would be to be the third best team in the west instead of the second one.
As an answer to this trade, Spurs will need to sign a random 7 footer. He doesn't need to be great or skilled and will get a lot of DNP CD but he will be useful against Howard to play some physical defense and gives his 6 fouls.