As both a maintainer of existing code and a dev for new projects, God, I hope so.

You're talking about a version of perl that will be 13 years old in April. When perl 5.12.0 was released, the current OS from Microsoft was Windows 7. The first iPad was released just nine days earlier. Android was still at version 2.something and was still the odd OS trying to eat away at Symbian's lead. The LTS release of the Linux kernel that was valid back then hit EOL in 2016. Moose v1.0 wasn't even a month old. If your boss came to you and demanded you write software that targeted any of those today, you'd think they got hit on the head with something pointy.

The Perl language has changed so much and enough bugs in perl itself have been fixed in that time that, for my own projects, I wouldn't consider burning too much time even testing against anything older than two maintenance track (typically even numbered) releases; at the moment, that would be perl 5.32 which is already nearly 3 years old.

In short, I'm more than okay with leaving the past in the past. However, I would also consider that a breaking change that might get a major version bump to the dist itself in a release that only includes that new minimum perl version metadata and/or use v5.xx; line. That's just smart deprecation policy.