I have also not seen any Wordpress core dev participate on an php-src internals discussion let alone something like the Framework Interoperability Group that outs out the PSRs.
Note I guess it might actually be that I did come across a Wordpress core dev, but maybe they just didnt identify them as such.
But without communication the chances of collaboration are low and without collaboration imho its going to be hard for Wordpress to identify and assess the potential for new directions.
That being said, Wordpress is king of the hill and it at least right now there is no indication of this changing. So changing might just have a ton of risks with maybe little chance of success. Then again I guess AOL once thought quite similar about their position.