TSN reported Sept. 26 talks were ongoing but a contract for the 22-year-old was not imminent.
"I still have the same level of confidence that we can accomplish what we set out to do," Dubas told Sportsnet on Sept. 18.
"It's our full intention that all these young guys are here for a long time, and the impediment right now is we're trying to go through a process with them, with [agent] Lewis Gross and William Nylander and their camp, and we'll continue to work away at it."
Toronto has played two preseason games without Nylander, who tied his NHL career high with 61 points (20 goals, 41 assists) last season.
"I don't care what workout you are doing, these guys are getting better every day," coach Mike Babcock told the Toronto Sun on Sept. 19. "You're at a rink someplace on your own, or maybe with one or two other people, you're not doing this.
"That makes it harder for you. But hockey is a business. Kyle and [the agent] will work things out and [William] will eventually find his way back here."
Toronto selected Nylander, the son of former NHL forward Michael Nylander, with the No. 8 pick of the 2014 NHL Draft. He has 135 points (48 goals, 87 assists) in 185 NHL games and eight points (two goals, six assists) in 13 Stanley Cup Playoff games.