The old saying in wrestling is "never say never" because someone might be dead-set against working for a certain company but then the circumstances change and a flat out "no" can turn into a "yes." Bill Goldberg and Bret Hart are names that we never thought we'd see work for WWE but time can heal wounds.
In the case of Chris Jericho, he was never opposed to working for Impact Wrestling but it was more to do with being loyal to Vince McMahon. Something must have changed because he is now saying that he would be open to doing something with Impact.
Dave Meltzer, who is close with Jericho and has known him for decades, speculated that Vince McMahon might have been unhappy with Jericho's match with Tetsuya Naio where he won the IWGP Intercontinental Championship. That might explain why Jericho has changed his mind. Jericho has said before that he had McMahon's blessing to work in Japan and he wouldn't work in the United States unless it was for WWE.
Jericho in Impact Wrestling would provide them with a huge boost as they look to gain the confidence of fans that have left the product since they were dropped by Spike TV in 2014. It also helps that Don Callis, one of Jericho's good friends, is one of the main people in management.
2018 has been an interesting year for the wrestling business but the latter part of 2018 and early 2019 could be the start of something big for Impact if they can get Jericho.