It's probably too late. The work they've done with blaze is wasted since react and angular(still) are dominant. The work they've done with MongoDB is wasted since most of the world wants SQL. So what do they really bring to the table. It feels like too little too late.
This prevents Meteor from being used in any environment that needs to/wants to use a SQL db.
This prevents Meteor from being used in any form, for any application that needs to access existing data in a SQL db.
React does not prevent Meteor being adopted - not having SQL support is a dealbreaker.
If Meteor does not confront and solve this problem nothing else matters.
The only thing MDG should be doing in 2016, is SQL DB support.