At any one time, something like 90% of all enterprises are engaged in at least one multi-year strategic move away from an abusive vendor. In the tech world, these might be Oracle, Broadcom, (formerly) IBM, or (even more formerly) Computer Associates.
Typically you're looking at a year or two of discovery, audits and planning, another year or two to cover the main transition, and then up to five years of mopping up.
There are other near-ubiquitous vendors (eg. Microsoft and Cisco) who manage to be tolerated as annoying rather than outright abusive. I guess they take a slightly different view of how hard to squeeze their customers.
I did a gig at a Fortune 500 that had actually succeeded in entirely eliminating Oracle. Life was still miserable.
They lived in fear of something slipping through the net. So print servers were switched off because they contained an embedded Oracle JRE. And deployment pipelines that used Hashicorp's Packer had to be rewritten to eliminate the VirtualBox plugin (despite it not being used). Office coffee machines were looked at with suspicion.
Every vendor had to be queried, every piece of software had to be tested and have appropriate controls put in place. There were pre-emptive audits and endless compliance procedures.
There was so much work involved that any cost savings must have been fairly minimal.
Typically you're looking at a year or two of discovery, audits and planning, another year or two to cover the main transition, and then up to five years of mopping up.
There are other near-ubiquitous vendors (eg. Microsoft and Cisco) who manage to be tolerated as annoying rather than outright abusive. I guess they take a slightly different view of how hard to squeeze their customers.