Everything you said is true, and you have some good points. But you are making an assumption that is not necessarily true. You are assuming that the interface

Everything you said is true, and you have some good points. But you are making an assumption that is not necessarily true. You are assuming that the interface, the part the customers see and use, changes so much that they require retraining. It would be entirely possible to re-implement the entire thing in another language with no discernible changes to the end user. The end user need not necessarily know that anything changed other than it is now moving faster since it does not have to go through an emulation layer and can take full advantage of the speed of modern hardware.