Avengers: Endgame might have been the thematic end for the MCU but it also set up a number of plot elements for future movies and shows. The most glaring example is how it set up the Loki Disney+ series when it had the trickster god escape with the Infinity Stone. Considering how secretive Marvel Studios and Disney can be, most people thought that this was done by design. However, that wasn't the case, if you want to believe the movie's writers.
During a live quarantine watch party where they tweeted out answers to questions through ComicBook.com, Christopher Markus and Stephen McFeely revealed that their reason for having Loki escape was done for a funny joke and nothing more. Marvel Studios clearly saw money in the idea, as they decided to base a whole Disney+ series on the event.
Loki will definitely explore the MCU's multiverse, something that Doctor Strange in the Multiverse of Madness will base its whole existence on. This had fans wondering if the character would also get involved in the sequel or if Chris Evans' Captain America will right his wrongs and get the Infinity Stone back. There's a multitude of possibilities that can be done and that's what makes this series so exciting.
Currently, the Loki Disney+ series is scheduled for a 2021 release, though that can always change due to COVID-19.
Read: Avengers: Endgame Script Reveals Marvel's Extraordinary Security Measures