But cleanroom implementations are meaningless if copyright can be asserted over the API. Clean room implementations only work because it has been generally understood that an API itself is essentially a directory listing, like a phone book, that in and of itself does not constitute some sort of creative work. Before the Oracle case, it was assumed that it was the code itself that constituted the intellectual property. But that is now apparently no longer true, and thus the Win32 API has gained the same level of protection as the source code.
If this stands, and is not corrected either by a lower court or by Congress, no one will every try a clean room implementation of any non-free library again, because there's a real likelihood that you would find yourself sued into oblivion for breach of copyright.
Wine may be safe because MS is being constrained by future potential anti-competitive suits, and of course Samba is protected because of a deal cut with the EU. But from this day foreward, clean room implementation of proprietary APIs, and I assume any other software spec (document format, communications protocol, etc.) will have absolutely no protection under the law.