No, in the sense that it doesn’t have a roadmap – it is in maintenance. If a developer got involved, upgraded it and tested it, I think jdf (Jonathan Feinberg) would probably accept the patch and make a new release – or / in the meantime the mode could just be released from someone’s fork and manually installed.
I honestly don’t know. It might be an easy drop-in replacement, or it might be a lot of work.
Well, 15.4 numpy would be bad news for JyNI, which Jython needs to load numpy. My understanding is that the latest JyNI (2.7-alpha5) is best able to load numpy 1.13.3. Later numpy breaks it Jython 2.7.2, NumPy advice · Issue #37 · Stewori/JyNI · GitHub
This is just based on what I have read, not experience.
That said, it looks like perhaps Trinket is using a hand-crafted partial numpy replacement running on Skulpt, since their target is JS, not JVM. I can’t tell. So that would have a completely different set of limits.