IMO, the main hinderance in this area has been the computational resources required to run the HTM algorithm. One project that I have always felt is a potential game changer is etaler, which brings GPU acceleration to the table.
Now, Etaler’s massive speed improvement does come at the cost of a couple functional deviations from the vanilla algorithm, but the detrimental effects of those optimizations are mainly theoretical (there are a number of posts on the forum which show etaler to be highly capable).
I would view Etaler as a good candidate for experimenting with scaling up lots of models and applying the SP and TM learning algorithms to new components of TBT (such as the lateral connections between CCs, for example).