TL;DR of @Lucas' article: first blaze has been more public than react for longer. But Blaze is a drain on Meteor resources, and react is more mature. They will start transitioning to using React underneath Blaze 2.0. React is more mature, advanced, but also takes longer to learn than Blaze. They recommend if you can take the time to learn React, do so. If you can't, then use Blaze but change how you use the templating. Don't reply on the implicit context of the template, instead.
But implying 'we already have react', blaze has been around for longer - changing the coupling of a whole framework takes time. I'm surprised that meteor is acting as fast as they are! Good job meteor team.