I'm still happy with Natalie Portman. I wouldn't mind her re-doing a few scenes being I'm sure she could do some of them better now, but she's still fine for me in the PT, as is Maul. Other than that, I could totally see everyone else re-cast minus the characters you mentioned.
Lee was great as Dooku, as was Sam Jackson as Windu.
Jango was good, a lot of the people were good. The one person I would really change is Anakin. Maybe someone like Jonathan Rhys Meyers; someone who can act.
Yes, I forgot about Lee somehow. Her was really good as Dooku, but Sam Jackson was not great as Windu, in my opinion, especially in TPM and 80% of AotC. He got decent at the end of AotC and was alright in RotS. He could still be replaced in my books.
I could have been more pleased with Shmi Skywalker, like every pilot in TPM, Jango's son should have his scenes re-done.