Will:

> LuaTeX will not be backwards compatible with pdfTeX in the generated
> output (i.e., two identical documents may have slightly different
> hyphenation/justification choices and therefore different page breaks).
> While the changes will obviously be rather small, I don't think anyone
> can really predict when pdfTeX will stop being used.

This means people will use LuaTeX for most documents (new
and when backward compability is not an issue) and the old
good (pdf)TeX only when strictly necessary.

At least, this what I intend to do. If LaTeX doesn't follow
LuaTeX, it will become obsolete even before it's born.

Cheers
Javier