Subban, who won the Norris Trophy as the best defenseman in the NHL with the Montreal Canadiens in 2013, was acquired from the Nashville Predators for defenseman Steven Santini, defenseman prospect Jeremy Davies, a second-round pick in the 2019 draft and a second-round pick in the 2020 NHL Draft. The 30-year-old had 31 points (nine goals, 22 assists) in 63 games this season.
"I talked to Taylor before we did this because he knows P.K., and he was really supportive, which I was hopeful," Shero said. "I wasn't sure what I would have done if he wasn't. We want to improve the franchise. Of course, we want Taylor to stay. Of course. We know that. He's under contract for another year."
Hall can become an unrestricted free agent for the first time in his NHL career July 1, 2020. He has one season remaining on a seven-year contract worth $6 million per season that he signed with the Edmonton Oilers on Aug. 22, 2012.
Acquired in a trade from the Oilers for defenseman Adam Larsson on June 29, 2016, Hall has 183 points (70 goals, 113 assists) in 181 games over three seasons with the Devils, including an NHL career-high 93 (39 goals, 54 assists) in 2017-18, when he won the Hart Trophy voted as NHL MVP.
He missed the last 47 games this season and had arthroscopic surgery in February to remove fragments from his left knee. He had 37 points (11 goals, 26 assists) in 33 games.
Shero said the fact that the Devils and Hall will wait to begin negotiations should not be viewed as a "red flag."
"He's a great kid and a huge part of our team and franchise," he said. "We haven't put a timetable or deadline on it. I don't want to get boxed in like that, because I think it's more important relationship-wise to be able to sit down with him.
"It's no different than what I would do with Nico Hischier. He's not going to be unrestricted, but he'll be eligible for an extension at some point, and I want him to understand what we're doing and just touch base. It's more than just money and those things."
Hischier, a center selected by the Devils with the No. 1 pick in the 2017 NHL Draft, can become a restricted free agent after next season. The 20-year-old had 47 points (17 goals, 30 assists) this season, his second in the NHL.