After Hong Kong vowed to sue Donald Trump at the WTO over plans to relabel the city's exports as "Made in China", trade law professor Bryan Mercurio discusses the debate over whether a case is worthwhile. In a busy week for US China affairs, trade talks appear to be back on, even as US lawmakers push to take punitive action against Beijing to the extreme. SCMP Hong Kong desk editor Denise Tsang is our special guest, unpacking why the Hong Kong government is so upset its exports to the US will…