I agree! Our work on TruffleSqueak [1] and on Polyglot Live Programming [2] has shown that it's possible to build language-agnostic live programming tools with GraalVM. If Espresso implements the required Truffle APIs correctly, our tools should also just work for Java. :)

[1] https://github.com/hpi-swa/trufflesqueak/ [2] https://github.com/hpi-swa/polyglot-live-programming