As part of an improved UI I would hope that i
f I rename an identifier to an identifier of a different length there will be an easy way to visit the sites of the renames to fix up formatting (primarily adjusting whitespace and/or lines that have become too long).
If the rename is not based on a strong semantic framework (e.g. in the C++ world something that can truly grok all of the name resolution rules) then there will need to be some means of incorporating human input (a la query-and-replace). If such querying occurs on a site by site basis then there could be a query respone that says "yes, do the rename but then pause and let me do some editing".
/john