You still need dynamic "pages". Things like geoip redirection or localization etc. You could in theory load this stuff via ajax, but this doesn't work for search engine crawlers. But i do agree most stuff can be static, you can push json on fragments onto s3 and have the web page fetch them via ajax.
We've done this for a lot of data vis work. Clients have access to a cms which lets them stage and publish their data. Doing so puts JSON files on s3 where we also serve the site. There are some trade offs, sometimes you miss having that rest api, but you also gain a lot too.
Route53 can do a lot of that localization redirection for you, though not exactly at the geoip level. Other localization redirects can easy be done from JS.
