I can't believe Perl is gonna die just because of "illegal" unicodes in the regex engine
In the past the perl interpreter would often crash or leave itself open to security holes when fed badly-formed utf8. Now it more often detects such cases early and refuses to continue (with just warning for a grace period to allow people to fix up their code).
There are 7,389 lines in the main perl interpreter C source which have the the text 'utf' in them. If you want to volunteer to do a thorough audit of every single one of those lines to look for, e.g. negative wrap-around, performance degradation and security issues, and want to write comprehensive tests for every case, for both 32-bit and 64-bit platforms, then its possible that the decision to ban code-points above 2^(N-1) might be rescinded.
But there really is no point. If you're feeding codepoints > 0x7fffffffffffffff into perl, something fairly major has gone wrong, and quietly ignoring those rogue codepoints is just masking the bigger issue.