As the Sony starts to ramp things up for Spider-Man 4, the question being asked of every actor who has appeared in the franchise so far is "Are you going to be in the sequel?" Elizabeth Banks, who played Betty Brant in the first three Spider-Man movies was asked that very question by CHUD while at the Zack and Miri Make a Porno junket, and her reaction was one of uncertainty.
"I'm the last person they call," Banks said. She also revealed that, depending on the size of the role, she might not even be interested. By the time of the third movie, Banks had little more than a cameo appearance. "If it's that small, I probably won't do it. They don't need Betty Brant. It's purely, at this point - and I don't think they see it this way - it's kind of a favor at this point."
When originally cast in the first Spider-Man, Banks was a relative unknown, and was happy to be cast at all. But since that time, Banks Hollywood star has risen steadily, so it makes sense that she wouldn't be all that interested in appearing if Betty Brant only has a small part in Spider-Man 4.
Now, that said, Sony could easily go either direction with Banks' character. It would be easy to cut Betty out of the film entirely, and it would be similarly easy to include the character in a major way in the story. Betty Brant has been a major part of the Spider-Man comics, having had a sibling who was killed during one of Spidey's battles, her husband being one of the people who assumed the identity of the Hobgoblin, and Betty herself was one of Peter's love interests while he was in high school.