Villa, who have never been relegated in the Premier League era, are rockbottom and eight points from safety with just 12 matches of the season remaining.
Ellis does not believe that there is any chance of his former team preserving their top-flight status.
"In the end, it's the players that are really responsible," Ellis told Sky Sports News. "Unfortunately, they've not been good enough this season.
"It's now a certainty that [Villa] will be in the Championship next year."
Ellis sold Villa to Randy Lerner in 2006 and also said that he was disappointed at the American's lack of regular appearances at Villa Park.
"I'm rather sad that the man I sold to hasn't given more of his time to come and see Aston Villa play," Ellis added.
Remi Garde's side next travel to Stoke City on Saturday afternoon.