Do I need Nginx with Gunicorn if I am not serving any static content?
No, I no longer deploy nginx specifically for the python app. I may have an application load balancer / nginx in the path to split requests to other apps, but not for load management. If using asyncio based systems, I typically don't even use an app server (uwsgi/gunicorn). This is including apps with very high throughput. Every layer of reverse-proxy / layer-7 load balancing will add a touch of latency- don't add it if you don't need it.
In a typical python server setup it is recommended to have Nginx web server serve the static content and proxy the dynamic requests to  Gunicorn app server. 
Now if I am not serving any static content through my python application do I still need Nginx in front of Gunicorn ? What would be the advantages ? 
Detailed explanation would be really appreciated.
All the static content is served through CDN and the backend server will only need to serve the APIs(REST). So when I will only server dynamic content, will I need to have Nginx ? Does it have any advantage in case of high load etc.