With an e-collar it may be possible, not sentences but one letter commands. The collar needs to be very responsive, Dogtra 282 is what I am using with my deaf lab. Using pager mode and working out morse code signals for specific commands.
So, no the dog may not answer in Morse Code, but you may be able to command a dog using Morse Code using an e-collar. I imagine it would be a good thing for a service dog and a person who could not speak commands due to a handicap. If this is an interest to someone I will post updates as I progress.