I don’t know why everyone thinks Echo is going to replace Pharah. Ever since they nerfed Echo’s Flight tech, her flying is very limited. Either you use Flight to peak over walls and take out an opponent with Sticky Bombs, or you use it to engage with your team. Flight is more like a positioning ability similarly to Moira’s Fade, then it is a flying ability.
Also, Echo is going to be on the PTR to at least mid (most likely end of) April, because of lockdowns and Blizzard being forced to work from home.