"Blaze is threatened by React". You can use React or you can use Blaze. If React becomes so popular that Blaze is not longer used, that's OK... nothing to be threatened about. It's nice that Meteor can move with a trend.
"Tracker and Minimongo might eventually disappear as well". Tracker and Minimongo aren't giant stick bugs near Australia that need to be preserved. It's ok if they are replaced. They are internal tools for Meteor provide its "reactivity". I doubt reactivity is going away.
Other non-scary things: Routing is solved by community packages. Pagination, forms... really? Server-side rendering has the "spiderable" package, but the SEO / server-side rendering problem isn't unique to Meteor.
The database issue is valid. Meteor uses MongoDB. But, you shouldn't go down the Meteor road and try to shoe-horn a relational DB into non-relational DB, then say WTF. You knew from the beginning that non-relational DBs have their own set of problems. My limited understanding is that MongoDB was picked because it was the easiest way to get the reactivity that the MDG was looking for. Meteor road maps says SQL support is on its way.
I don't know where the OP is going with this. Maybe this is the part 1 of the late night TV commercial where they list all of our problems (think Slap Chop), then in Part 2 he'll solve all of our Meteor problems if we buy the next book he writes.