I agree on this too. To the extent it should be considered time-limited, it should be «until N releases after sysvinit is removed» or somesuch, if that happens.
In legal terms, in law, it would be considered that the burden of proof lies with those who want to remove it.
Asking the supporters of those scripts to prove that they still need them would be considered an unreasonable burden.
The burden of proof would be laid with the ones who want to remove it.I think any kind of time-limited removal that you pronounce in advance, is irrational.
"My grandmother used that" is not a good reason.