Over the weekend you may have seen a report from a New Mutants test screening that said the new cut of the movie screened (which is now much shorter at about an hour and forty minutes) had no connection to the Fox “Singerverse” of X-Men movies and that the characters didn’t know what Mutants were. Both of those things are true.
The part that probably isn’t true is that those edits were done to force the movie into the MCU and be the Mutant’s introduction to the Marvel Cinematic Universe. People seem to have a short memory as many sites claimed that the Dark Phoenix delay was to add that movie to the MCU. As we all know that wasn’t the case.
One big reason why it’s unlikely that New Mutants would be “side loaded” into the MCU is due it still being a Fox production and the Fox producers would then receive a credit on any future MCU movie where these characters appeared. That’s unlikely something Feige would want to happen, especially with some of the same people involved with Dark Phoenix being responsible for New Mutants. There’s also not a single MCU movie that Kevin Feige didn’t produce, which would be a big issue with adding New Mutants to a carefully orchestrated movie series.
In reality the reason for cutting any ties to the “Singerverse” in New Mutants is likely more connected to the failure of Dark Phoenix than trying to put the movie into the MCU. That movie bombed so badly that it cost Disney $170 million and negatively affected the entire company’s third-quarter 2019 earnings. Cutting ties to that universe would be a way to prevent the stink of Dark Phoenix from hanging over New Mutants.
At San Diego Comic Con in July, Kevin Feige made the first even official Marvel Studios mention of the Mutants. He obviously does have a plan for how they fit into the MCU, and it probably doesn’t involve shoehorning in a Fox movie the company has little faith in.