It’s an interesting question becauseI find it hard to distinguish between what I think will come and what I wish for.
I expect the next thing to be an update for the ER-301. Just a more powerful CPU board, fully compatible to the existing module. And while I believe there is development work on it done in the background, Brian has already stated that this will come when the OS is fully matured as there will be a new OS necessary for the new CPU and the following development path will not be compatible to the presently existing OS.
What I wish for and what would be more of a ‘new module’ would be an ER-301 with event related gate/trigger outputs for the ER-301. I think this is a bit of a realistic hope since Brian did insinuate that if ever some kind of expander comes it will be something like this rather than a CV out expansion.
What I dream of would be a ER-501. A Control Voltage Computer in the vein of the 301 with a lot of inputs, outputs and internal patching of CV algorithms and sequences. Complex CV is something I would love to achieve in an easy accessible way as known form the 301. Although I am not sure if it would be to much of an overlap between the 101, the 301 and teletype. Maybe with the new CPU an expander that allows CV and gate/trigger output would already cover this in a better/simpler way.
The ER-301 already can do nearly everything and I do not see much need of something else than more power and more connectivity. There is a lot to explore in software units that is not possible by now.