The best way for Lady Sif to return to the MCU would have been a role in Loki episode 4, where a time loop induced by the TVA forced Loki (Tom Hiddleston) to repeatedly relive a past encounter with her.
Prior to MCU return in Thor: Love and Thunder. However, she ultimately appeared ahead of that movie in Loki.
While her surprising Loki cameo was received well by fans, a part in Shang-Chi could have worked out even better. On the surface, an Asgardian warrior like Lady Sif doesn’t feel at all like an obvious choice for a kung fu epic, but it actually would have felt quite fitting. Similar to the situation with the Abomination (Tim Roth) and Wong (Benedict Wong), Sif could have been one of the combatants participating in Shang-Chi's fighting tournament. An Asgardian, a kung fu expert, a Hulk villain, and a Master of the Mystic Arts all competing in the same event certainly would have been a fun concept. Including characters that represent different cultures and fighting styles is an important element to martial arts tournament movies like Mortal Kombat and Bloodsport, which is why Lady Sif would have been an asset to Shang-Chi.
Not only would this have given the tournament an additional MCU fighter, but it would have made a lot of sense for her character. Asgard is gone now, leaving Sif without a home. She of course could have relocated to Valkyrie’s New Asgard on Earth, but since she wasn’t in Avengers: Endgame’s final battle, it’s likely that she’s off on her own somewhere, possibly as a loner hero. If her ties to the Asgardians have been severed, Lady Sif's MCU return would have made more sense if she was putting her fighting skills to the test by participating in Shang-Chi’s tournament.
Plus, Lady Sif being in Shang-Chi and the Legend of the Ten Rings would have been a great deal more exciting than Loki’s time loop, especially since it did little to set up her MCU future or address what she’s been up to in recent years. Unfortunately, Sif’s whereabouts and current activities are set to remain a mystery until Thor: Love and Thunder releases in May 2022.
