From my point of view, many will jump to Swift if given the chance.
https://developer.apple.com/library/prerelease/ios/documenta...
Additionally, this is just version 1.0. So nothing rules out that if Apple sees the language being widely adopted, other improvements in the FFI area aren't made.
The only Java apps of the era that I remember used non-native UIs, and were painful.
Whereas I'd be shocked if Swift wasn't adopted wholesale by iOS developers.
Rather back when Mac OS X 10.0 was being released and Apple was unsure if developers would be willing to write Objective-C code.
They created their own JVM, with Objective-C runtime support (JavaBridge) and let the developers choose.
At the same time, Apple representatives did sessions at UNIX heavy user groups, like CERN, where they sold Mac OS X as a better BSD, and Java as first class language was part of the feature list.
As they saw developers were comfortable adopting Objective-C in their toolchains, the JavaBridge was dropped.