[shyneeup]

I think one of the reasons why it's such a conundrum is because software development as a practice is just now getting to the level of complexity where large groups of people have collaborated over a large codebase over a long time.

One of the problems that the microservice architecture is trying to solve is by making a a large software entity a collection of smaller easier to manage entities. It's like single cell organisms evolving to multicell organisms...each cell becomes smaller and simpler and more specialized and replacement of cells becomes easier and allows the overall lifeform to "scale" and become more complex.

Mature software companies have gone through this transformation multiple times already in the form of, n-tier, SOA, microservices, and now serverless architectures. This is all part of a natural progression of making individual components simpler, the overall structure more granular, and as a result more resilient. This resiliency opens up new capabilities to scale a complex system.

My long winded point being that legacy software will always exist yes, but each piece of legacy software is already getting smaller and more granular where rewriting it will eventually be a more continuous operation of refactoring small things--kind of like skin cells falling off your body or hair falling out.