I'm not a gambling kind a guy, but I would wager everything I own that the answer to that is NO.
Trains, even Monorail trains are not like a car. They are expensive, are renewable and made to last. Over the years, I would guess that that whole fleet has been completely replaced on every level except the shells and I'm sure even some of those have been upgraded. The one thing I can tell you is by now every single one of them has millions of miles on them in theory, but in reality the inner workings, motors, transmissions, axles and other parts have been replaced, probably more than once. So the only thing that hasn't been made new is the design. They aren't as old as the years they have been there.
The claim that they are not being maintained fails to pass the logic part. They have been running that fleet for almost 40 years. They don't go far away on any trip but if it runs even just around Seven Seas all day, probably averaging 10 to 12 hours per day, almost every day for the past 40 years, if not extremely well maintained all that would be left is a heap of shattered fiberglass and rusted pieces parts in a landfill someplace. If it were cheaper to replace the fleet than it is to keep them running dependably, they would do that in a heart beat. Or they might just replace them with a gondola expansion. But I don't see any new monorail trains in any part of the future. I suspect that as soon as they start to have issues with the rails themselves (concrete also has an expiration date) they will start to sting up the gondola cables and that will likely, really be a thing at some point and since the rails are as old as the park to MK and the Epcot ones are only ten years younger.