There’s a belief by some on the internet that when Spider-Man shows up in Sony’s Universe of Marvel Characters it could be a different Peter Parker but still played by Tom Holland. With the official information we have right now, it sounds like that isn’t the case. There would be MCU references allowed, while it still being Sony’s universe.
According to Deadline that is what Marvel and Sony are planning to do:
We hear that as Sony progresses their own Marvel universe with titles likes Venom 2 and Sinister Six, and Disney/Marvel their own, there could be a “call and answer” between the two franchises as they acknowledge details between the two in what is would loosely be described as a shared detailed universe.
The wording there is key, “details”.
They don’t need a big explanation of how Peter Parker traverses cinematic universes. People are speculating Doctor Strange and the multiverse, but what Deadline is talking about sounds a lot simpler than a complicated plot device showing him jumping between universes.
From what Deadline reported, it sounds like Spider-Man can just show up and Sony would be allowed to make references to key details in his backstory, perhaps things like Tony Stark or The Blip. Likewise if something really major happens to Peter Parker while appearing in the spinoffs, Marvel could reference that if they need too.
That way Sony and Marvel can share Spider-Man, and it doesn’t require them to do mental gymnastics and write around Holland’s now five-movie history in the MCU.
It doesn’t sound like wither Marvel nor Sony want to recast Spider-Man, so Tom Holland can indeed play the character into his 40s. The “shared detailed universe” that Deadline describes seems to be the compromise to allow both companies to use the character without needing to reboot him or create a different version of Spider-Man for each cinematic universe.