Even without the utter decimation of disease, they still have the issue of political disunity. Europeans can still set them against each other in ways they might not necessarily have before, even if the Europeans might not always gain from it. The Mississippians in particular are where this POD might be interesting. They don't seem to have formed particularly large states, but they did form states (going by de Soto and likewise the archaeology of Cahokia and nearby regions). Since European technology will filter in from the East Coast first, this could put them at a temporary disadvantage from eastern groups which they will be more equipped to overcome earlier, since they have more organised societies. They still have the advantage of numbers and organisation. The reintroduction of the horse to North America will go differently than OTL, probably filtering from the east or southeast.
I could see Europeans settling and suceeding up to the Appalachians, beyond that is where it gets tricky since they might help reinvigorate the post-Mississippian cultures. I'm not sure how vulnerable those societies were to Spanish-style conquests where Spain imposes their authority in place of the indigenous leaders--I'd imagine moreso than East Coast natives, but less than the Aztec or Inca. There's also the issue that there's quite a few of them to take out. Because of this, you could easily have the trans-Appalachia region (basically the Mississippi and tributaries watershed, with another possible divide between north and south based on economic factors) become its own nation, based on the hugely different colonial history. Speaking of that, the end result is that the US/Canada looks far more like Latin America OTL in terms of ethnic makeup.
If you want to get into Latin America, I think we can rule out anything like Cortes or Pizarro happening. Mexico might be like India, where Europeans colonise it through exploiting native states. The Inca might as well be the China of South America. The rest of the continent, I'm not sure--the rest of the Andes could be like the rest of Asia, maybe colonised, maybe not (since butterflies are huge at this point). Argentina, Uruguay, and Southern Brazil might be seen as a parallel to the East Coast of the US in this case. The European demand for sugar will make sure the north of Brazil sees some colonisation.
Incidentally, this might result in more Native American slavery. Aside from the reasons of the ease of escape, another reason it was never practiced in large amounts was their relative vulnerability to disease compared to Africans. Butterflies on the African slave trade (slightly less demand) as well as in the lands of the American Indian. Mexico and the Mississippi basin could become important centers for the slave trade. The main destination is the Caribbean as OTL, which I can't see Europeans not succeeding in destroying the indigenous populations.