How CxOs survive legacy

Scot Nielsen at Rocket Software outlines the key considerations and most common myths surrounding IT modernisation projects

 

For CxOs navigating today’s enterprise IT landscape, legacy is both the starting point and the storm. Inherited systems, often running core business processes, dominate the estate. They power payroll, logistics, billing, customer data - and yet they are frequently invisible, poorly documented, and resistant to change.

 

Calls to modernise come from every direction: regulators tightening the screws, developers demanding better tools, and boards expecting digital agility. The CxO stands in the middle - whether they carry the title of CIO, CTO, or CFO. And the pressure is mounting.

 

 

The illusion of reinvention

The allure of modern architecture is powerful. Today’s best practices often begin with a blank slate: migrate everything to the cloud, replace legacy languages with modern ones, adopt microservices, and enable continuous deployment pipelines. It promises elegant simplicity - flexible, scalable, and future-proof. The architecture is built to adapt, not just to perform. Teams can release quickly, fail fast, and fix fast. For many, this is the ideal: a system that invites change rather than resists it.

 

But anyone who has lived through a rewrite knows better. Projects overrun. Requirements shift. Embedded logic disappears. Business risk escalates. Why? Because optimism collides with the scale of legacy. What looks simple from a distance becomes complex up close.

 

It’s like planning to renovate a house, only to discover the plumbing runs through the walls you meant to knock down. For organisations with decades of code, data, and process, the clean-slate rewrite often reveals itself as an illusion - ambitious, yes, but rarely practical.

 

That doesn’t mean modernisation is off the table. It has to be approached differently - and when done right, it delivers. Progress becomes visible, risks are contained, and systems that once felt immovable begin to respond to change.

 

More than that, legacy starts to behave in the true sense of the word. It earns its place by adapting, not just persisting. And if that feels hard to believe, ask yourself: why have these systems endured for so long? Recognising the answer is the true state of IT meditation - a quiet acknowledgement that endurance, paired with adaptability, is a powerful asset.

 

 

Rethinking the narrative

Modernisation isn’t about choosing between old and new. It’s about understanding relative benefit and relative risk. A fully reimagined system may offer ultimate flexibility, but the risks - disruption, delay, cost, knowledge loss - are significant.

 

Incremental modernisation - introducing modern tools, APIs, containers, CI/CD pipelines - can reduce delivery times, improve integration, and ease developer onboarding. It may not deliver the clean lines of a total rewrite, but it can move the organisation meaningfully forward. A small step in legacy modernisation often equals a giant step in delivery.

 

 

The legacy reality: skills, scale, and fear

Legacy systems are hard to update for several reasons. Skills are scarce. The scale is enormous. And it’s often intimidating because nobody wants to be the one who broke the system that’s quietly run the business for thirty years.

 

Conversely, there’s always the gung-ho call to “rip and replace” - a rallying cry for a clean start, often without a full appreciation for what’s at stake. It sounds bold, even visionary. But without caution, that cry can become a eulogy: RIP - not just the system, but the stability it once ensured. And not least, the CIO. Ambition without restraint, when it meets the true scale and complexity of legacy, can turn bold plans into career epitaphs.

 

Yet dismissing legacy as a problem to erase ignores its value: decades of business logic, compliance awareness, operational resilience, and straight-line performance optimised over time. These systems weren’t designed to change quickly - they were designed to run reliably at scale, with predictability. That doesn’t make them obsolete. It makes them proven.

 

Systems like the mainframe still run much of the world’s core enterprise transactions. Far from being a relic, the mainframe offers a level of reliability, security, and throughput that many modern platforms still strive to match. Rather than discard legacy, the more sustainable path is to evolve it - make it observable, testable, and changeable. Leverage what works, modernise what’s holding the business back.

 

 

Surviving the Wave of Demand

CIOs face a wave of frustration. Internal teams want faster delivery, product owners want digital-native capabilities, auditors demand compliance. At the same time, non-legacy experts weigh in: consultants suggest full rebuilds, cloud providers urge wholesale migration. “Move to our cloud,” they say, as if infrastructure alone solves everything. Under pressure, there’s a temptation to promise transformation at scale.

 

But credibility is built through delivery. The CxO who shows tangible progress - modernising a key system, integrating cloud services, reducing a manual process - shifts the tone. Frustration gives way to confidence. The conversation becomes about what’s possible, not just what’s broken.

 

 

Regulation as catalyst

Regulatory pressure can be a useful forcing function. Laws like the Digital Operational Resilience Act (DORA) and NIS2 demand resilience - pushing CIOs to modernise not for fashion, but for auditability, continuity, and control. External urgency creates internal alignment. It sharpens the case for change and opens the door to investment.

 

 

Getting strategic

Surviving legacy isn’t about tactics - it’s about strategy. That means:

1. Assessment first: Know what you’ve got. Understand application value, technical debt, and interdependencies.
2. Roadmap second: Decide what gets retained, what gets replatformed to the cloud, what gets retired, and what gets refactored.
3. Communication always: Align stakeholders. Set expectations. Share wins.

The CxO who leads with strategy and delivers through action, builds trust. Over time, calls for radical change become opportunities for measured progress.

 

Ultimately, legacy is not the enemy; but it can’t be ignored. The CxO’s job is to translate urgency into execution, ambition into architecture, and noise into momentum. Modernisation doesn’t have to mean starting again. It means starting where you are - and knowing where you’re going.

 

---

 

Scot Nielsen is VP product management at Rocket Software

 

Main image courtesy of iStockPhoto.com and alengo