Yes, it is reasonably accurate to say there were forgotten agricultural/citystates in the Amazon region, that are being re-discovered. Though a lot of research remains to be accomplished by verification is a proven fact. And, just as Tenochtitlan, there may have been series of successor states of different waves of ethnic/language groups. But with little cultural mingling, except for copying or improving on major structures such as pyramids, that the newcomers found left behind by the preceding culture. As available technology usable in tropical areas is reinvented but not improved, due to the natural scarcity of tropical farming land/storage capability and other resources.
As Brazil continues to develop it's space program, the use of radar-mapping satellites will provide new sites to investigate. There may still be surprises out there to confound all of our assumptions.
For anyone who is interested establishing a long term research project, I am of the opinion, that the future archeologist should consider exploration of the coastal shelves. An ambitious and expensive and risky route to new discoverys. But, as our technology improves this would be a virtually untapped field that could explain lot of the inconsistencys hindering our understanding of that historical period when the lower ocean levels provided routes for our ancestors migratory wanderings.