If I remeber right costal Brazil wasn't heavily populated in that era. Thus we may see Portugal keep its foothold. As for place like MExico, there were pleanty of other reason's for their downfall including the enimies they made. I think Spain, or someone is likely to stir-up strife in that area and studdenly we get Mexico to look like various to be like India, with several princidoms risesing up against each other. Much more poltical intrigue. This will likely build a buffer between any attempts to reach further south though which will allow the Inca to sort out their differences, prehaps coming out as strong as European nations in just a few decades.