This presents a fundamental challenge to large-scale technology migration. And one of the greatest ironies.
Possession of the required new skills is the least important contribution from your existing team. Yes - you read that right. During this transition, what makes your existing team so valuable is not their technical skills. So what does?
- Domain knowledge
No matter your business, there is specialized domain knowledge. Mine is healthcare. That means deep understanding of patient registration, ordering medications, patient care documentation, and scores of other complex workflows. These don't change with new technology. Your team has spent years learning these and the interplay among them.
- Customer understanding
Your team understands how your customers operate at the intersection of the current product and the domain. You can't do a migration without some consideration for your customer base. Your team has customer relationships and trust (hopefully) to increase the chances of the transition going smoothly.
- Organizational knowledge
As I wrote last time, you may supplement your team with expertise in the new technology. These folks aren't going to have a clue about anything related to the items above. Your team can help them navigate the challenges of finding information about the existing system and processes - or even who knows the answer in the first place.
Returning to the challenge - changing who a person perceives themselves to be. Your goal is to shift that perception. You have to state (and restate) that technology is fleeting - and that it can be learned. The emphasis for the existing team is on their knowledge of domain, customer, and organization. That can't be extinguished by Java 8, HTML 5, or any other technology.