i don’t think there can be. tumblr’s draw isn’t any features it has (apart from maybe homepage customisation, but you get that with a website) it’s the features it lacks (algorithms, etc). and it’s the community, which was curated by a lot of coincidences at the right time.
you’d need to get everyone to up and move at once, with the ability to reblog posts from old tumblr. i think it’s unreplicatable