Yea, I think Dan is okay with the type cast thing, since he is also involved in major productions. Sure, he will always be known as Harry Potter, but I believe he is in safe water.
Not sure about Rupert Grint, I think he is in the most danger with the type casting just because he hasn't been in a lot of other things.
Emma Watson (from reading interviews and such) shows more interest in school and maybe doing something else besides acting. She might even do both (wish I hope!) I believe she is safe though too.
Of course, everyone will remember them from Harry Potter, but if they put themselves in other major movies or productions, I believe they can convince us otherwise