there are indeed some doubts about these, but that still leaves us with 30+ species and a few others waiting for further investigations to see if they are indeed new species or just local variants. And large parts of the Amazon are still waiting for a taxonomist to be explored. I think that the number of saki monkeys will be (further) reduced, but there are also some variations of woolly and spider monkeys that need to be investigated. So I am expecting some descriptions of new species in the future. Most of the recent new species are not really a result of splitting, but more of new research.
I still expect based on recent trends in primate taxonomy that with better genetic research we will see more lumps and more species relegated to subspecies status in the future. That said I am more familiar with African/Malagasy species and ungulates when it comes to taxonomy and the diversity of S-American primates can be something of a pandora's box and with quite some of the original literature in spanish/portuguese it isn't very easy sometimes....
For Woolly Monkeys the recent papers that included genetics all argue for lumping instead of splitting, Spider Monkeys I have never looked into...