Dr. Hawkins presented this road-map in his latest talk:
Is there any article/literature available for the third step that includes how L4, L2/3 and L6a work together?
I have watched the latest HTM School episode Grid Cells (Episode 14) several times and I have understood how grid-cells encode information on a map collectively without the need for a map but I need to have a solid overview of how everything relates to each other in order to build the next HTM version. I have implemented a spatial and temporal pooler to work in Objective-C/Xcode for iOS devices and it works great so far!