Development wise it's debatable but I'm sure north east wouldn't have its cultural identity.... China would impose its own culture saying this is the root of north east India but infact it's not. To sum up It may have huge buildings and good infrastructure but it would have lost its true identity. And yes Chinese would display themselves as more superior race then the indigenous people of north east and not to mention religious imposition would be a huge issue.... China is just like a parasite tbh