That reform has already been done. It’s called – or should be called – the #InternationalStandardCalendar, as constituted by #ISO8601 (Part 1 at least).

AD 1 = 1 CE <=> 0001 = +0001
BC 1 = 1 BCE <=> 0000 = ±0000
BC 2 = 2 BCE <=> -0001 = −0001

– century: 20
– decade: 202 (deprecated)
– year: 2026