I thought it was becoming more universal, but now I'm not so sure.
grep on the Mac used to use PCRE regexes if you used the -P option (`grep -P ....`), but beginning with OS X 10.8 the -P option was removed, so an important place that used to offer PCRE (default grep on a default Mac) actually removed support for it. They didn't replace it with something better; they just took it away. Maybe a Unicode issue?
Not only is PCRE not universal, overall support might even be waning.
grep on the Mac used to use PCRE regexes if you used the -P option (`grep -P ....`), but beginning with OS X 10.8 the -P option was removed, so an important place that used to offer PCRE (default grep on a default Mac) actually removed support for it. They didn't replace it with something better; they just took it away. Maybe a Unicode issue?
Not only is PCRE not universal, overall support might even be waning.