The writer's comments come as the government has said it will launch a consultation into the privatisation of the channel.
The channel was founded in 1982 and is owned by the government at present, receiving funding from advertising. However, it could be sold off to a private buyer.
Davies said we are "looking at very dark days here" while addressing the matter at the Banff World Media Festival in Canada.
He added the channel’s remit “which is to make shows like It’s A Sin” would change if it were to be sold off.
“It exists to make this kind of drama and that’s going to fall away now,” the former Doctor Who show runner added. “Come back in 10 years and you’ll see. I can’t promise we’ll be here to talk about this sort of programme on Channel 4 for much longer because the government is gutting it.”
It's A Sin aired on the channel earlier this year and was made available as a boxset on All 4 upon its launch.
It centred around a group of friends living in London throughout the HIV/Aids crisis in the 1980s and was a hit with audiences and critics alike.
Read more: What to watch after It's A Sin
Channel 4 previously said the programme drove its streaming service to record growth.
The Department for Digital, Culture, Media and Sport said earlier this week that moving the channel into private ownership could ensure its “future success and sustainability”.
With additional reporting by PA.
Watch: Sir Elton John and Olly Alexander raise awareness for HIV at Brit Awards