I think they will lose some already established studios that can afford to retool and reskill on another engine. But I think the vast vast majority of current unity developers are breathing a sigh of relief that they /dont/ need to reskill or retool on another engine.
Unity is still on shaky ground, but they have been since they went public. They need revenue, and their big ad revenue plan got ruined by dastardly apple protecting users’ privacy. Couple that with an upstart and promising engine following in Blenders footsteps. In five years, they might have lost every hand they had left to play. Irregardless of the missteps of the last week.