Even if the Native Americans were able to stave off Disease and initial European Conquest, I pretty much see the Americas becoming a situation like India was. The European Powers carving out large Spheres of Influence, pitting the Natives against eachother and doing a slow Assimilation/Conquering through large political games. Failing even that, the Scramble for Africa would probably be turned into a Scramble for the Americas as well. The Native Americans just dont have the Technology base or the Culture that allowed Rapid Industrialization and mass Military Campaigns that allowed them to control Africa and the Indian Subcontinent, and have Spheres of Influence in China.