Make all operations with FULLTEXT index faster.
Proximity operators
Support for "always-index words". They could be any strings the user wants to treat as words, examples are "C++", "AS/400", "TCP/IP", etc.
Support for full-text search in MERGE tables.
Support for UCS-2.
Make stopword list to depend of the language of the data.
Stemming (dependent of the language of the data).
Generic user-suppliable UDF preparser.
Make the model more flexible (by adding some adjustable parameters to FULLTEXT in CREATE/ALTER TABLE).