It would certainly be possible. I am hoping to do the same for Tetrapad as well. I was hoping it would be done earlier in the year but other developments took place and we’re still nailing down the I2C API for the Tetrapad, so the Teletype implementation hasn’t happened yet.
For Planar 2 the module is a lot simpler (you don’t have a whole ton of LEDs to deal with in addition to sensors etc) so it would actually be a lot easier to implement an I2C interface for it. The header on the back is for this purpose…