Comment by selkin

This is a useful Gedankenexperiment, but I think the replies suggesting that the conclusion is that we should replace Kafka with something new are quiet about what seems obvious to me:

Kafka's biggest strength is the wide and useful ecosystem built on top of it.

It is also a weaknesses, as we have to keep some (but not of all) the design decisions we wouldn't have made had we started from scratch today. Or we could drop backwards compatibility, at the cost of having to recreate the ecosystem we already have.