An angle on this that may work is to just introduce the new tech on something not very important but still useful. A decent argument can be that plain old tech

An angle on this that may work is to just introduce the new tech on something not very important but still useful. A decent argument can be that plain old technology upgrades at some point are going to be gigantic herculean efforts if the same old language/framework is used for a long period of time. And you are more susceptible to security issues and/or ridiculous "extended support" contracts the longer a tech is kept around - to the point where it is difficult to patch, etc.