Na época,
Thanos had two of the infinity stones, space and power. Neither of them give any particular ability to see through illusions. Loki's "trick" was to swear fealty they stab someone in the front; that is not a trick worthy of a god of mischief. Unless Loki was suicidal he had plenty of time to try something to avoid death; on the other hand, Loki's tricks are almost always illusions, and this one looked like his physical body.
No entanto, podemos trapacear:
Tom Hiddleston had a 6 film contract with Marvel. -- Thor, The Avengers, Thor: The Dark World, Thor: Ragnarok and Avengers: Infinity War makes 5. He is a popular character and they have the rights to the actor for 1 more film.