You don't even need nginx; I've got a single Node process on a Heroku "hobby" node serving my site, and it's weathered several front-page visits peaking at 15 requests per second without problems. The important thing is the static-rendering (assuming it applies for your site's content)
Having a blog post of mine get posted to HN (many years ago) was how I discovered I'd accidentally introduced a bug into my web server config that meant the app server behind it was serving the static assets as well as the dynamic stuff. It entered a state of wedgitude quite rapidly when traffic ramped up.
