Moves to the cloud began with the low-hanging fruit: email. 

What exactly is it about email that made its cloud migrations so ubiquitous? Everybody uses it in the exact same way and very rarely are companies adding value by managing their own email, said Jeremy Roberts, senior research analyst at Info-Tech Research Group, in an interview with CIO Dive.  

Consider email the gateway solution that brought even the greatest laggards to the cloud. The tool has brought in big money for providers.

Microsoft, the clear enterprise software as a service market leader, increased revenue in its productivity and business processes segment $6 billion to $35.9 billion in 2018, a 20% year-over-year increase. 

The segment, which includes LinkedIn, commercial and consumer Office and Dynamics, was buoyed by a $2.4 billion revenue increase, 11% year-over-year, for commercial Office 365. The solution includes Exchange, Skype for Business and Sharepoint and reported growth in subscribers and average revenue per user. 

There is life after email and companies adopting cloud-based solutions are considering what's next for adoption, from easy wins to legacy architecture. According to Forrester, about 20% of enterprise applications run in the cloud. 

The 80% gap creates ample room for companies to modernize systems and for vendors to increase revenue streams. 

The "tenor of the conversation has changed" with cloud applications, Abby Kearns, executive director at Cloud Foundry Foundation, an open source cloud application platform, told CIO Dive. A few years ago, companies were primarily discussing proof of concept or small, greenfield applications. 

"We're actually starting to see more mission-critical workloads" move to the cloud, she said. To make the cloud shift, companies are writing applications for, and refactoring in, the cloud. 

This falls in line with another shift Cloud Foundry is seeing — organizations are pivoting from trialing multiple solutions from different cloud providers and consolidating on one primary provider. 

Applications on deck for migration

The path to 100% cloud-based options is winding and unrealistic. Sensitive workloads could remain on-prem long term. 

Outside email, the logical next step application migration is something people use in the same way, where customization takes place at the application layers such as in HR information systems, according to Roberts. 

Disaster recovery is another logical next step and developer test environments also find a natural home in the cloud. 

Easy cloud-shift wins give way to migrating complex business applications nested in a company's technology stack. A year-and-a-half ago, Roberts was working with a logistics company to migrate applications to the cloud, including its public-facing website and email. 

The company had a price estimation algorithm that was used to estimate the cost of moving goods between point A and point B. 

"Foundational and fundamental to their business," the application was heavily integrated across its environment; the business called it a "hairball," Roberts said. Too complex to shift to the cloud, the company decided to start migrating applications around the edges "until the hairball was unwound a little bit."

As Roberts notes, the cloud migration process is often painful but there are options. Amazon Web Services offers six application migration strategies called "The 6 R's": 

• Rehosting — lift-and-shift

• Replatforming — which AWS calls "lift-tinker-and-shift"

• Repurchasing — buying a new solution

• Refactoring — rearchitecting an application for a cloud-native environment

• Retire — end of life

• Retain — the "do nothing for now" approach, according to AWS.

It's still early in migration, in the next three years, industry can expect tremendous growth in the number of workloads moving into the public cloud, Kearns said. At the same time, the number of on-prem workloads is going to grow too. 

Hybrid cloud or multicloud is going to continue for many years, Kearns said. "It doesn't make sense to put everything in the cloud," she said. "A lot of the work around AI and ML is really going to drive a lot more workloads to stay on-prem."