Every day that Singletary remains is a wasted day in the resurrection of this team.
The current players and other coaches cannot be properly evaluated while they are under Sing's system. If he stays until the end of the year, whoever does next year's draft and acquisitions will be working in the dark, just guessing at how good the personnel really are.
If Sing stays the year, next year will be ruined as well.
It is absolutely necessary to fire him now, not at the end of the year, immediately, for the future of this team.