Anyone suggesting push on without them wants their heads examining.
We struggle with credibility with the RL WC as it is. If Aus and NZ don't come, the likely final would be England v Fiji or Tonga. With full sides they would both be competitive....Tonga could probably win the WC over England atm....but the obvious driving force behind this is the NRL....not the governing bodies, who have simply rowed in.
So if not safe enough for Aus and NZ NRL players to travel, the NRL islands players, who make them competitive are not going to travel either. So realistically you're looking at islands sides from local players on the islands or the NSW cup (Championship / lower SL level).
On that basis....england have a procession to the final, probably not winning a game by less than 40 pts, with the final itself probably a 40pt thrashing. It is a non event!
Quite simply the only realistic options they have are i) get them back onside ii) defer to next year iii) create some sort of micky mouse NZ and Aus sides based on SL players (or worse a combined Australasian side....This is RL...I would not put it past them)
i) is extremely unlikely now they've gone public and were probably looking at 1-200k daily cases by the time it comes around. iii) makes the game look a joke, although in true RL fashion is probably the most likely

, in which case the comp is probably dead in the long run as sponsors will inevitably withdraw.
The only sensible one is ii) Next year.
Bring it forward by a week next year so the final finishes before the Wendyball WC. Gives you a perfect platform to market it as back to back world cups....get your flags up early, and pull in some football fans to go to matches etc!