Yes, I know, I still have another timeline but hear me out. What if after Henry VIII finds out that the Legatine Court ruled in favor of Catherine, he utters the fatal words "Who would rid me of this troublesome wife?" and some ambitious knight overhears the King's half-meant words, jumps at the chance, and assassinates Catherine in broad daylight expecting a reward? What would have been the repercussions of Catherine's assassination in England and the continent?
Highly implausible. Becket was actively opposing Henry II politically; he didn't have to. Catherine was Henry's loyal wife; nothing could be said against her save her infertility, which was not her fault (Henry blamed himself for provoking God's anger by committing incest by marrying his brother's wife). Murdering her would be an outrageous crime, much worse than killing Becket, and that was bad enough.