Now don’t go running off and posting on Blogs, etc., that The Lizard will be the villain in Spider-Man 4! This is not an announcement, but instead producer Grant Curtis talked to iF Magazine about who he thinks would make a good villain:
For me it’s hard to beat the Lizard, it truly is. That’s just me talking. I think the Lizard has got a great story of not only personal pain but also emotional pain, and trying to mask both of those, it’s a strong storyline. The Lizard has always been a favorite of mine, even before working on these movies. I’ve always liked Kraven The Hunter, but he’d have to be used selectively. For me though it would have to be the Lizard.
It is, of course, very possible that The Lizard will become the (or one of the) villain(s) in the fourth film, but it’s just too early to tell.
Source: iF Magazine