There are three big hurdles between electronic shifting and my tandem.
#1 - Price. The current price is insane even for the average upper middle class bike geek. Maybe someday.
#2 - Field repair. I don't know about your stoker but mine does not put those shoes and clothes on to walk. Even a 20 mile ride can leave you 10 miles from home where even the most helpful stranger can't carry your tandem. This may be addressed some day by some sort of manual emergency feature involving a cable from the derailleur to the captain....
#3 - Triple - No matter what cassette you put on a double it is still not a triple. SRAM likes to claim there is no need. They are right I have no need for SRAM shifters on my tandem if they will not handle a triple.