Common tropes in software for this: * Switching from polling to push or vice versa * Merging two overlapping systems into one * Splitting one system into two

Common tropes in software for this: * Switching from polling to push or vice versa * Merging two overlapping systems into one * Splitting one system into two * Rewriting from language X to Y * Moving from centralized to decentralized or vice versa * Moving logic from one layer to another (eg smart client vs thin client)