Nobody really expected them to do a smaller scale spin-off next like this instead of the full-fledged sequel right away but it's pretty smart for a lot of reasons: slowly expands the scale and scope of the games instead of us just jumping into the next one with the playable Peter and Miles everybody expected with Miles also learning the ropes all the while. Instead he gets the spotlight being thrown into things on his own like Peter did starting out.
Narrative-wise that will definitely be a great way for Miles to shine as a character because he doesn't have Peter around to help him or play second fiddle. It's kinda like him starting out in the comics with Peter being absent (dead there), but he still has his own solid motivation here with his dad's death instead of relying on Peter dying.
Here it's like we'll get to have the cake and eat it because everybody will get both characters and we'll get a story next time with two likable Spider-heroes we've both spent plenty of time with that get to team up together, all the while Sony sells more PS5's out the gate (and ensuring even more down the line, probably) and gets to put out more titles with the popular license.
As far as speculating what villains might show up, that's an interesting thing to think about. Prowler is probably a shoe-in. Bombshell might be a good candidate also. Can't really think of any other villains at the moment. Can't really think who the purple tech people he fights in the trailer might be working for (I mean the purple does make one think Prowler).