I think you need to compare the fate of newer e-sports endeavours like heroes of the storm which were very heavily inflated by blizzard support, and those that

I think you need to compare the fate of newer e-sports endeavours like heroes of the storm which were very heavily inflated by blizzard support, and those that evolved a bit more from grassroots like starcraft or dota to see what's sustainable. The starcraft scene has weathered its decline as blizzard lost interest and while it's shrank to a more manageable size, is still clearly capable of continuing without blizzard doing more than not shutting down the game servers (the SC1 scene, not even requiring that much). While heroes of the storm collapsed without Blizzard, as will overwatch.