In July 2014, I wrote that we were working on a new native InnoDB data dictionary to replace MySQL's legacy frm files.
This is quite possibly the largest internals change to MySQL in modern history, and will unlock a number of previous limitations, as well as simplify a number of failure states for both replication and crash recovery.
With MySQL 5.7 approaching release candidate (and large changes always coming with risk attached) we decided that the timing to try to merge in a new data dictionary was just too tight. The data dictionary development is still alive and well, but it will not ship as part of MySQL 5.7.
So please stay tuned for updates... and thank you for using MySQL!