Mississippi Rice+Bronze Age New World, would look more like MR*BANW or maybe even MR^BANW.
In terms of development prior to contact with euros.
Now I think this one issue should be given a special attention. Say that the *Arawaks managed to develop the advanced navigation technics as per BANW(when was that in that TL ? 100 AD or 500AD ? I don't remember....
Also, I'm especially curious about whether there will be even more relatively civilized nations springing up especially due to the influence of *Arawakan network, in places like Florida, Central America east of Maya, or on along the coast of *Gulf of Mexico, just north of the lands of the Nahuans(which IIRC was inhabited by agricultural people), by the natives of the respective mentioned regions, though, not by *Arawakan and/or Mayan colonizers.....
I agree that losses from the new diseases would be very high, in all probability, close to a half, and, maybe, much more than a half of pre-contact population.
On the other hand, Jared in his LoRaG presumes that Eurasian and Aururian ground wouldn't be as virgin as American ground in OTL: suffering from their own plagues, the Eurasians/Aururians had built up non-specific immunity, allowing them to survive even previously unknown epidemics better than it was the case in the Americas, where native population was almost entirely without 'plague experience' (well, with possible exception of syphilis).
With more developed New World and Australia, it could mean that there'd be no completely virgin ground anywhere in the world: all civilizations would be able to survive transcontinental plagues with losses less than in the OTL Americas, while all of them would have their own germs, obstructing colonization attempts.
On balance, I'd say that proposed AH-world would see technological (and, probably, social) development slowed down, as well as very little of European settler colonies, with non-European states surviving almost everywhere in the world.
Though I'd say that at least in the New World the Europeans would at least be successful in the Atlantic side of North America,South America south of Amazon, and at minimal a portion of Caribbean archipelago.