Well rolling updates aren't the end of the world. If your site is hosted with multiple running instances, each instance will be taken out of the load-balanced loop, brought down and updated in sequence, so your users shouldn't experience any real down time.
One option though would be to move to a non-resx based localization setup. you can write your own ResourceProvider to override the built in one. Rick Strahl had a nice example of reading resource information from a database.