Schema aware transformations

Is it feasible for a schema aware processor to detect unreachable
templates?

I've just been editing a stylesheet after a DTD has been updated and on
a few occasions I've really had to study the DTD to check whether a
template match still applies, eg:

template match="a/b"

Element b still exists, but no longer as a child of a.  It's tempting to
just leave the template in 'just-in-case', but it would be really useful
if the xslt processor would highlight this (of couse, as schema's
replace the DTDs).

Equally, any typo's in the match would also be highlighted.

I asked a similar question in November '04
(http://www.biglist.com/lists/xsl-list/archives/200411/msg00355.html)
but here I'm interested only in template match patterns, rather than
'void' xpaths.

Ultimately I really want to start using SA processing but I can't find
the justification just yet...

cheers
andrew