Certainly, one can architect anything, use NoSQL for critical data storage, or use Kafka for synchronizing two SQL databases with the same schema and living on

Certainly, one can architect anything, use NoSQL for critical data storage, or use Kafka for synchronizing two SQL databases with the same schema and living on the same netowrk(an actual proposal from a fan of microservices, btw). But whether it should be done is another question, and I have yet to see a single example of microservices being a good idea. Not "it works" -- obviously, you can get it to work, but being better than alternatives. Come to think of it, Mongo is the same...