For those who remember the transition to .NET from the Vantage 6 VB Client, this sounds all too familiar. If you told the folks back then that you’re fighting to keep that client, they wouldn’t believe you. 
For example:
Well, staying on the sustaining .NET Framework certainly isn’t a long-term option. Like VB6, the technology stack of the current client will receive less and less support and more importantly will be more difficult to secure.
What is more possible with Kinetic than Vantage is the ability to make external apps that easily upgrade. With REST and Epicor functions, one can completely skip the new UI and write your own web applications that enforce your business logic. 
It will also be easier to integrate Kinetic into other web applications by creating components that are embeddable into Teams/SharePoint/SalesForce/Dynamics/etc. reducing the amount of context switching that the old client had. And finally, this architecture will make it easier to use progressive web apps to provide offline capabilities to mobile devices like phones and tablets.
Will it be a bumpy ride? Yes. Yes it will be…again. Will it be worth it. IMHO, very much so.