I'd be happy if the Smallville finale was the last hurrah for Williams' theme, because the Donner, pre-Crisis version of Superman is finished and should be left to rest in peace.
I also don't think that today's generation cares all that much, if at all, for that theme and it would have little to no significance for them, which is a problem when you stop to realize that we're not the target audience for a Superman flick now. The current/new generation of fans needs their own version of him for the movie property to be successful. I liken it to my complete ignorance of the "Lonely Man" Hulk TV theme being played at the end of Incredible Hulk because I was too young to remember that theme, therefore it held no significance for me and I didn't even recognize it.