Modernization of IT cannot be seen as purely a number of technical changes. As systems change, the people and processes supporting that system, and the people using it, also need to change.
Do not expect IT modernization to be just an IT thing, instead, consider changes to the business side as well. Users will need to be trained on using new systems, and support needs to be able to answer their questions.
Depending on the company, users might embrace change, or reject it as they have “always worked” a certain way.
Likewise, the IT department might need to train its people in new programming languages, certify them to use new products, or change internal processes to allow technical changes to bear fruit. This is a process that takes time and effort, both from the company and the individual, which both must be willing to invest.
Perhaps certain skill sets will become superfluous; can the people with this skill set be re-trained and given new tasks? If new skills are needed, is the company able to hire people with those skills?