INCAS SURVIVE!!!! Where do they expand?

[Lenwe]

Well they were just raiders, and the Incas assimilated all the ethnic tribes in the Andes, and if they fail at that, human sacrifice always works. Besides, the Inca Population lived in the mountains for centuries at this point, which there more adapted to then the Europeans, in fact, they evolved features to deal with the hostilities of the Andes. They evolved larger lungs and larger fingers for plant harvest.

They'd have an advantage of a Conquest of Patagonia.

Not, they don't, most of the habitable zones of chile are at relative low level above sea, 500 meters or so.

The principal problem that the spanish have in his conquest of Chile, is that the andes don't have a plateau south of Antofagasta, and that most of the country south of the Bio Bio river was Cold Jungle, the so called Valdivia Rain Forest.
https://en.m.wikipedia.org/wiki/Valdivian_temperate_rain_forest

Here a photo of the place todas after years of logging and farming

 

[Escape Zeppelin]

One advantage they have I think would be that like the Romans they were really good at asimilating cultures.

I think they were better at cowing their conquered neighbors than actually assimilating them. After all they were still an extremely new empire and the Spanish conquest showed they had a lot of enemies. In a short period the Spanish managed to raise native armies numbering tens of thousands of the Inca's previously conquered peoples.

If the Inca survive I think they expand east over the mountains and into the Amazon. I'd argue that while their survival is certainly possible I don't think that they can hold their extreme north or south against the Europeans and the political and social unrest they bring, or local revolts. They may even lose the coastal area. East of the mountains however is well known to the Inca, easily defended, and almost inaccessible to the Spanish.