I agree that Mexico will most likely have colonisation like India/Indonesia.
But the Inca will have to deal with a major epidemic (25-40% death rates), as well as European influences which would rather favour multiple competing states in the Andes instead of one state.
Oh absolutely. But you could say something similar of the Roman Empire after the Antonine plagues, or of China by the midpoint of the 3 Kingdoms period. My point is that the conquest IOTL caused delegitimization and disruption orders of magnitude worse than a "mere" population collapse and political division. Here the
idea of a unified Andean empire will be hard to put aside. Incan laws, concepts of kingship and government, language, customs, et cetera will color the whole side of the continent. The civilized world may be divided, but prior to unification no one would have thought of the region as being "the civilized world".
I suppose Quechua would spread regardless, although it's noteworthy the degree the Spanish spread Quechua in places like Ecuador which TTL would be lacking.
Some things would be absent, but at contact the Inca were quite a young state. It's difficult to imagine scenarios in which an additional century or more as
lingua franca doesn't strengthen the imperial language greatly.
Inca ideology IMO vaguely reminds me of Chinese or Japanese thought.
I know next to nothing of it.
What was it like? I don't suppose you could point me towards a source?
The Mississippians were already in decline because of drought, and disease as seen OTL would finish them off. I don't think more or less Europeans in the 16th/17th century would do too much either way. Although it's noteworthy that since there's no Pueblo revolt and a slower introduction of horses, the Great Plains will be horseless for a lot longer.
Well, that's sort of the point, no? More gradual contact suggests disease experiences not seen in OTL.
As for OTL's collapse, what do you want to bet it was the corn? (Triggered by drought, of course.) High yields create large populations, severe soil depletion requires more and more exploitation to support those populations, and the labor-intensive nature of the crop guarantees that a crisis above a certain threshold will be self-reinforcing. Corn induced sharp failures in urban centers and extended crises in less centralized regions throughout it pre-contact use. Heck, it seems to have given the Chinese some of the same trouble after they began exploiting it.
My thought is that, like most corn-induced declines, the Mississippian one would have been uneven. A lot of marginal communities with less-depleted soil would have (probably did) survive, to receive substantial numbers of refugees/migrants from the former centers. These might develop further. Meanwhile, in the old heartlands, soil would gradually begin to recover.
As I said before, it's certainly plausible to end up with the same results we saw in OTL. Indeed, that may be the most likely outcome. But TTL is, potentially, a more survivable crisis.
The Amazon is a more likely locale for a change than the Mississippi, certainly. If the circumstances are right.