But the missing factor is that if the OF left, you wouldn't have the rest of the teams remaining in roughly their current state and just moving a couple of rungs up the ladder. There'd be a void to be filled domestically, and if a couple of the big teams still left capitalised on that void then they could become bigger and start to dominate, and there would be a new monopoly of sorts (perhaps not as strong, however). What you would want is for several teams to grab a chunk of the pie left over to prevent one or two getting a significant advantage. That'd help maintain the competitive equilibrium among the other clubs. But maintaining an equilibrium like that over time is damn difficult in any league. In a close league, all it takes is for a team to hit a purple patch and win back-to-back titles, start getting the lucerative European places regularly. If they manage it properly they can build up a big gap between themselves and the rest of the field very quickly. From that point they become virtually unassailable. I agree that Scottish football would be far better without the OF, but a sharp divide between the select few 'haves' and the multitudes of 'have nots' is an intrinsic aspect of the European football landscape. Holland is a perfect example of this.
I realise that and I am certain that clubs like Aberdeen and hearts would pick up more championships than the other teams. But it would not be on the same scale as the Old Firm. The 'biggest' clubs (i.e the clubs who can get access to the most money) will always win more trophies but the gap between the likes of Hearts and Aberdeen can never become as big as the gap between the OF and the rest. the OF have become artificially 'big' clubs due to a number of reasons which guarentees that they make so much more money than the rest, nobody else will have that advantage.
I think even without the OF you would have a breakaway top pack that would share the top few spots between them. As you say, at the moment there is often a good diversity of teams in spots 3/4/5 amongst the remaining clubs. Get rid of the OF and this competitiveness would translate for a while into genuine competitiveness for the title. But after a couple of years the teams that are able to compete best will pull away from the rest of the pack and you'll be left with a Dutch-style situation with only a handful of clubs with a real shot at the title. In a small market, the teams that can grab that lucrative European access have a huge advantage over the rest. Anything's better for Scottish Football than the OF though.
A handfull of challengers is better than the same two over and over again. I agree with what you are saying but don't you think other teams like the Dundee clubs, Motherwell etc at least would know that, getting a good manager in, laying good ground work and building a team would give them a shot at the title, at the moment, nobody has that.