Perhaps, but if we discovered a mechanism that was orders of magnitude more efficient or higher bandwidth then any rational species would just naturally use it to replace EM communication.

I mean just imagine some alien engineer trying to use EM for a new mobile phone system when everyone else on planet Glerbulon is using DE. The other alien engineers on the team would be like “wtf are you using photons for? Are you nuts? Just use an off-the-shelf unobtainium link. Here I’ve got one in my pocket.”

Well, people do maintain obsolete forms of communication because they can & or have specific circumstances requiring them. Thats why I am skeptical others would completely abandon a communication technology - there would still be the Globulon Technical museum hosting anual morse code transmision relay with steam powered spark gap transmitters between specially selected nodes in the local dyson swarm.