Isn't email mostly consolidated to a handful of providers with published APIs? (Office365, Google, Yahoo) I'd be curious to see the market share of just those 3 combined.
And they don't have any incentive to move to this.
And they don't have any incentive to move to this.
Perhaps for individuals and small businesses, but certainly not for large organizations, many of whom are running their own Exchange (or whatever else) servers.
Unlikely, but seems plausible to me.