For this E3, I can easily see Splatoon tournament instead last year's Smash Bros.

Any game that can be played by a team has a common characteristic: the closed team that keeps communicating almost always win. This becomes more clear as the size of the teams shrink. It was awesome to gather my team at TLOU and go play online all day and win every single match simply because we had a single coordination.

Even situations that you cited like searching the area with less ink to cover it and help a team mate can be improved with coordination, because you can comunicate and decide who (1 or more) will go to area/player X and avoid situations where everyone leaves the position to do redundant tasks.

You know what, yes i think so. I thinkk this can be a an esports game in the future. 

You're basing this again on games like TLOU, from actually playing both these games I can tell you communication doesn't add as much if anything at all to Splatoons team play as other shooters, the game is designed in a way that bypasses what you're saying. The only common characteristic Splatoon has with other team games is that you have a team, the are already commands to tell team mates to come to you or spread out, the map tells you the the rest of what you need to know. Voice chat won't change much else to the teams play, matches are chaotic encounters that can't be dictated by what you're saying and in many cases I found teams that tried to emulate that lost because the concept of spreading Ink doesn't rely on it.

I have not played and no interest.