I'd just like to pop by to say: I have no Idea. But, it is likely there will be a 4th sequal. Just look at the differences in release dates of the first three and take a guess. They usually follow a regular cycle, unless they have something special in mind.
<font color=red>"My name is Ozymandias, King of Kings:
Look on my works, ye Mighty, and dispair!"</font color=red>