While NOTHING is outside the realm of possibility, I think somewhere, deep down inside even Iger and Chappie and others understand that the monorail is synonymous with the US Disney parks.
The age of the trains in of itself is not the problem. Seriously. Delayed or deferred or just plain not enough maintenance is. We are hearing some positive steps are currently being taken in that regard. Hopefully, that trend will continue. I am hoping this situation is similar to MyMagic+, the huge costs (that ballooned even higher) to implement that system took virtually all of the investment from the parks. They're playing a bit a of catch-up now. The monorail is finishing up the automation program, now that it is wrapping up, hopefully we will see maintenance increase on the trains and beams. Again, we seem to be getting underway with that now, we just need that momentum to continue, and maybe even ramp up a bit, as they are now playing catch-up there too. The current fleet is a very different animal than any other Disney fleet in history.