It was never (and probably will never) be the dominant code due to the RU home nations plus, it's International program.
Also, Union is part of the Establishment and even IF we could get to the stage where we had more to offer, we would still be coming second in this country.

Having said that, as a full time pro sport, we should be ahead of Union in many other areas but, due to the gulf in revenue coming into the respective sport's, League will always be trying to play catch up and getting "mocked" by the media as it keeps on with it's innovative ideas.

Ok, an 18 team league.
The current 12 teams plus:
Toulouse
Toronto
Newcastle
Leigh
Bradford
London

This increase would mean each club would get around £1.8m a year from the TV money rather than £2.5m. Which sounds like a big drop but IIRC it's about what they were getting before the "new" tv deal.
Play every team once.
Play half the teams twice.
Gives 26 games per year.
Top 8 playoff like in NRL giving a max of 4 additional games.

No P&R.
Clubs will be assessed properly every 5 years. With proper targets given for growth/improvement in certain areas.

Lower division clubs can apply to enter and would expand the competition, not take someone else's place. Same goes for if a club goes under, it's not automatically replaced by someone else.

SL clubs must run a reserves side.

SL clubs to be entered into the Challenge Cup 2 rounds earlier than at present.

Standard club season tickets (as we know them) to be abolished. You now buy a Rugby League season ticket that includes the home SL matches of the club of your choice. It also commits you to buy a ticket for cup and playoff home games (like in football).
The price will be raised to also include entry to events such as Magic Weekend, Cup semi finals, mid-season internationals, Championship summer bash etc.

At the start of every season a 40/50 man England initial squad will be selected by the England staff. The players selected in this squad will then be restricted to playing a max of 25 games for their club in that season (excluding Cup & Grand Final).

Increase the number of marquee signings to 3 per club but include a 50% tax that goes to central funds specifically for marketing and development in specific areas. So say if Leeds wanted to sign a top player and pay him £200k per year as a marquee player, they'd have to pay £100k to this central fund too. The tax would be reduced to 20% for clubs in the bottom half of the table.

Just a few thoughts...

I reckon the game needs cleaning up first to increase intensity in matches. There is too much time wasting and conning the ref during the game these days, the PTB is a total mess and probably needs a few rule changes in these areas. It's not a consistent high pulsating game anymore and not very attractive to promote as an exciting dynamic sport.

That's purely down to how strict the ref's are.
It can be stopped instantly if that is what the game wants to happen and it's got naf all to do with how many clubs are in the top flight.

The reasons given for reducing the number of clubs in SL was to increase the intensity in the weekly rounds but, the demise in form of Leeds and Huddersfield (plus maybe, Saints) has let everyone else off the hook and we have seen very few games so far, where both competing teams have been at the top of their game for the full 80. Maybe it will happen in the super 8's but, if this is the case, then, this is no different to the old play offs.

This may be an early indicator that the new system is not working as expected.

Clearly, every minute doesn't matter. However, we have seen THE most unpredictable season in SL history and perhaps in RL history.

Going back to how many clubs should be in the top flight. Again, the game must have a strategy for expansion and growth of the game and not just make it up as we go and the governing body needs to sell the idea to the current fans of the game and then to new fans but, don't hold your breath.
It wont happen.