A preliminary web search seems to indicate that the answer is currently no.
Does anyone know about plans to support java on Win 10 IoT?
The answer is indeed "Nope". Microsoft Windows is a bit more "closed off" so I wouldn't sit around and wait for Java to come to IoT any time soon. If you want Java, go with a Linux distro like Raspbian.
Regarding your added note:
In the same analogy, you are coming to a swimming pool asking if you could surf here, because you were a surfer for 15 years somewhere in the Pacific. Yes it's a shame you can't surf in this swimming pool, but if you really want to surf in a pool, maybe look at an Intel Compute Stick.
Two years passed and Azul systems (as I understand not without the help from Microsoft) developed Java for Win 10 Iot
Not much is known about the performance/stability yet.
Windows want to push C# because it's their personal language, but yea, if you want java just go with some linux distro. (Raspbian for instance.)