The idea of a knockout being held during origin is perfect.
It solves the issue of teams like Brisbane, Melbourne, suffering in the NRL without half their team.
Play Origin three weeks in a row (which would aid it's on going promotion, rather than it being broken up spread across several months). During origin, clubs participate in a knockout cup. For the likes of Melbourne, they're premiership chances aren't disadvantaged by origin and they can give young guys a run in the cup with nothing to lose. For the likes of Souths, they're back in with a chance. Disappointed fans have something to cheer about, with a fresh start (if only for a few weeks - or just one game).
For everyone, they can rest some stars if needed or give young up and coming blokes a go, try things out.
Run by the NRL but a seperate comp - even separate the TV rights! This could accomodate clubs financially if they were to lose an NRL home game for the year (if the season was shortened by a couple of rounds).
The big question... where would the games be played??? Just random home ground advantage? Or neutral venues - SFS, ANZ, country towns?