Trouble is, even if it works, it wil kil itself.
If this goes ahead, and the predictions are all true, it will strip the best 400 players away from their current leagues, killing the leagues, killing internationals, killing the world cup and killing the unions.
Which will suicide for the new thing in itself, because eventually, those 400 players retire, and... there's nothing under them, and nothing behind them.
Without internationals, the unions are at serious risk, which puts the grassroots at serious risk.
The professional clubs all go to the wall as there's no audience left for them, so there's no academies to concentrate and coach the best talent. No professional clubs to them pay anyone outside of that top 400 to play rugby, and spread awareness of the game.
No international game to polish the best professional players, and to garner name recognition, so that the new league would want them.
Without the world cup, world rugby goes bust, or massively denuded financially, so no growth of the game to combat all of the above.
None of which is to say that it can't or won't happen. Theyll need more than £500M, just for player salaries, but throw enough money at it, and it'll happen.
There won't be an audience for it, or at least, of enough of one to actually sustain it, but that won't matter, because there won't be any players either.
Professional rugby will be dead, and the Saudis, or whoever else, will move on to another sport to try and clean it's image up with.
I just can't see the benefits, but a whole host of risks.
But hey, some rich **** get to play fantasy rugby for a few years, whilst not actually giving a damn.