There will be New paragon portraits
From D3 community manager: This is a request the community has been making since the announcement of endless Paragon levels. I'm happy to share that we're currently working on adding new Paragon portraits in the future, and we're planning on implementing them in an upcoming patch. :)
New Paragon Portraits will be added for every 100 levels past level 100, and ending at level 800 (so at 200, 300, etc.). All existing Paragon portraits from 1-100 will remain as they are.