Not that this is the definitive answer by any means, but simple measures like SO trends suggest that the community has moved on a bit[0].

Obviously I don't think that's definitive proof of Meteor being dead, but usually it seems like that's an indicator of declining new interest (which leads to extinction over time).

For another example, while I wouldn't say Backbone.js is completely dead[1], it's hard to pretend that it hasn't been largely supplanted by React and ES6, and Backbone probably doesn't have a bright future. There's undoubtedly a community around it still, but I would be shocked if that community doesn't get smaller each year.

I don't doubt that Meteor will continue to live for quite some time, but I think there's valid reasons to suggest the community will continue to shrink.

0: https://insights.stackoverflow.com/trends?tags=meteor

1: https://insights.stackoverflow.com/trends?tags=backbone.js