I think the pressure to change it will come from Celtics absolute domination over 13 of last 14 years with no sign of it letting up.
The lack of competition is stifling their European abilities and will start to affect TV audiences. Brendan Rogers is already on record stating a smaller league doesn’t work, whilst hinting towards a bigger league.
I believe if SPFL polled the real customers (the fans) via a season ticket holder survey, the outcome would be for bigger leagues and less repetition of opponents, but SPFL do not see fans as their base customer base, they see Sky as it.
Parkhead, whilst sold out every week is rarely full, fans are bored with the same repeated 4 or 6 times a season, and buy their ST to secure a seat for European nights, Rangers games and cup finals.
The local sports pub here used to show the old firm games, and pub was pretty full for them. Games were also on Norwegian TV. Old firm games no longer are, and if pub shows game it’s on 1 screen in the corner, the appeal is dropping. Scotland games though still pack out the pub, so it’s not a lack of ex-pats.
Longer term for Scottish football and especially the national team, bigger leagues allow to bleed young talent, play attractive football with less fear of 1 defeat dropping you from a top 6 position to a relegation position.
Personally id like to see a top league of 16, with 30 regular league games, playing each team twice only. I’d have a second tier of the same or 18. 2 straight up and down, with a playoff for a 3rd place, in a normal 2 semi final, 1 final format.