There will be no relegation from Super League in 2020.
The Rugby Football League (RFL) said the decision was made “for reasons of integrity, player welfare and also to protect the solvency of clubs”.
The news came hours after Toronto Wolfpack said they would take no further part in the 2020 season because of “overwhelming financial challenges” posed by the Covid-19 pandemic.
The RFL also said the 2020 Championship and League One seasons will not resume.
A survey of the Championship and League One found that the majority of teams would not support playing behind closed doors.
Instead, teams will be invited to play in a competition in the autumn that will celebrate the sport’s 125th anniversary, with a prize of £250,000 on offer.
Canadian outfit Toronto had been playing in English rugby league’s top flight for the first time after winning promotion from the Championship, but have opted to withdraw from the rest of the campaign.
The Wolfpack say they still “fully intend to field a team in the 2021 season”.
Toronto, who will also be withdrawing from the Challenge Cup, said in a statement: “This decision has not been taken lightly, and in consideration of a range of factors specific to the club as the only transatlantic team in the league.
“Greatly reduced ticket, sponsorship, merchandise and game day revenue streams have resulted from the loss of all 11 of the team’s home Super League games in Toronto.
“The Wolfpack would be left covering significant additional costs simply to complete a season of games in the UK, including Covid testing, stadium rentals, medical costs and player pay increases to align with the rest of the league.”
BBC Sport reported on 15 July that Toronto could be forced to pull out because visa issues may have prevented seven of their players from taking part.
They were bottom of the table when the season was suspended in March, having lost all of their opening six games.
The club say they will now be working with Super League and the RFL to “understand” the process with regards to next season.
In a joint statement, Super League and the RFL said they were “very disappointed” to learn that Toronto would be withdrawing after “firm assurances had been received as recently as last Thursday” regarding their participation.
“The club’s decision is especially disappointing given the imminent restart of the season,” the statement added.
“Our immediate focus is on getting the season back under way on 2 August and meeting the needs of our host broadcaster, Sky Sports.”
‘We’d heard rumours for months’
Toronto had been due to face Hull Kingston Rovers in the first game of a triple-header at Headingley to mark the restart of the season, with the teams scheduled to have met again two weeks later on 16 August.
Hull KR chief executive Mike Smith said Toronto’s withdrawal will have “an impact for the game and for the sport”.
He told BBC Radio Humberside: “We’d heard rumours for weeks and months about the situation, but we just got on with running our own club.
“[But] it’s not great when one of the Super League clubs just pulls out at this late stage.
“The problem we have is we were onto version four of the fixtures because it was such a minefield trying to put so many clubs in a short period of time and cram in as many fixtures as possible, with overseas travel to France now in the mix as well.
“Now potentially from 1 October there could be home games as well, there’s quick turnarounds, the Challenge Cup to fit in with some teams still in, so I’ve an awful lot of sympathy with the fixture committee.”