A few years ago the USGA Quintavalla study demonstrated that higher swing speeds actually suffered a small decline in the yards gained per mph of swing speed. They attributed this fall off to increasing inefficiency of the strike as club head sppeds got higher. For the most part though, the red line in their chart following shows that the yards gained per mph is pretty much linear at 3 yards per mph.
I took the liberty of adding three other lines.
The blue line is a mythical wet dream for the 99% and the ball companies (who would make a fortune marketing such a ball) which would give slower swingers a step up in trying to catch the big hitters. In my opinion, this ball will never exist - it defies the laws of physics.
The yellow line is what the 10% roll back crowd want to happen - a ball that dials the top back 30 yards and the 90 mph hitter on 22 yards. This effectively changes the slope of the line - again I don't think that'll be physically possible.
The orange line is what will most likely happen in a 10% roll back at the top end. The 90 mph swinger will end up somewhere around 190 yards. Not very appealing to me at least.
By the way the way the easiest way to regulate, implement and enforce a roll back would be to reduce the initial velocity and ODS standards and make the ball either a bit bigger to increase drag or make the ball lighter. No need to get into spin or dimples or other impossible to regulate areas.
Is it possible that balls could experience another quantum leap in distance under the current regulations? Not likely in my opinion. The current initial velocity and ODS standards mean that a ball can't get any faster off the club head and still conform. Unless someone can invent a ball that has improved aerodynamics that reduce drag then I don't see how a ball will travel further if it's launched with an initial 174 mph. Current practice has optimized the launch angle and spin rate for maximum distance.
The only loophole that I see that exists is that new, stronger, lighter materials are used in drivers so that they can be swung under control at higher than 120 mph. There are, of course, already long hitting pros that swing faster than 120 mph, and achieve ball speed that exceed the initial velocity of 174 mph. The USGA and the R&A could close that loophole by just maintain their initial velocity and ODS standard where they are but have them tied to a 130 mph swing speed.
I suspect that the creep in the PGA Tour average distance is the result of survival of the fitest - longer players are joining the tour and knocking off shorter hitters. I also suspect that would happen whether the courses are longer or shorter. Length is a competitive advantage.
As a sidelight, I spent some time this week in a simulator with a Slazenger Supremo persimmon driver I picked up in Scotland this summer, Callaway Epic Sub-zero and a Bridgestone E6 and an old Tour Balata 90 and Professional 100. The latter two have dried out over the years and have lost a gram or 2, so they may not be representative. I also used a graphite shafted Wishon cavity back thin faced 7 iron that had the old standard loft and my current Mizuno JPX EZ 7 iron that is 3 degrees stronger (so close to a 6 iron from the old days).
Fifty years ago in my prime I used to hit my Wilson Staff 7 iron 150 yards. The Wishon 7 iron was on average maybe 10 yards shorter that my prime despite the graphite shaft and thin face. The EZ was right around 150 yards. So, clearly I've lost distance to age.
The sim I was in measure ball speed pretty accurately. With the Epic I was getting ball speed around 135 mph and occasionally as high as 140 mph. That translates to about 220 yards in the real world. The long hitter on tour get up to 175 mph ball speed and above, so 40 mph higher than me, so they should be 110 to 120 yards longer. That sounds about right.
With the persimmon driver and the modern Bridgestone, the ball speeds were around 120 to 125 mph, so 10 - 15 mph less. That should translate to say 35 less yards. It is difficult to pick up the relatively heavy and a lot smaller persimmon driver and hit it solid, although I could do it in the 1960's.
In my prime I used to drive it about 225 yards, so I haven't lost much, if any distance with the modern driver, although I have lost it with the irons.
I tried the Tour Balata and Professional with the persimmon driver and there was a slight loss of 2 or 3 mph in ball speed - surprisingly small considering the age of the balls.
The conclusion I would draw from this is that the driver is just as much, if not more of a culprit than the ball in the distance gains.
At my age and current playing abilities and length I'm not interested in a roll back. I don't play competitively and I don't think I would have more fun if I was regulated back to driving the ball 190 yards. I'm already moving up a tee. I don't play any of the classic courses that are being desecrated, in the view of many, to compete with the distance of the elite few, so I'm not really concerned about that either. My current modern home course has tee decks that go back to 7500 yards and nobody plays them, not even in the Canadian Open Monday qualifier. I doubt there'd be much saving in maintenance by letting them go fallow. Perhaps they make a good nursery to patch up other tees that need work.
As for bifurcation, I can't see any reason why the PGA Tour, who are in the entertainment business, would want to make their players shorter. Distance sells, I think.