Somehow, if in this alternative past, there were no reactive resin coverstock, I think we'd have more participation than we do now.

I think fewer bowlers would believe that they could easily beat the more skilled  and the bowlers who invested more of their time and energy into learning the finer points of bowling. This is as opposed to he current "finer" points of bowling which is how can I get more revs and more ball speed.

I don't think the innovation of urethane had nearly as much impact on scoring as did the invention of resin. If I could put numbers on it (and I'm not sure this is really valid), I think the increase provided by urethane over plastic coverstock might be 2:1 or 3:1, the increase of resin over urethane might be 10:1or 20:1.

I think bowling could have survived the advent of urethane; I don't think the sport of bowling will survive the advent of resin.Some other counterbalancing method to offset the power of resin needed to be implemented. Maybe something like insuring the depth of the gutters were always legal; like deadening the elasticity of the side boards; like changing the weight and balance of the pins. Maybe; I'm not sure.

Also, think of how core technology AND use has advanced. While there were some good cores used in urethanes before the resin era,most ball design developers thought having a core flare was a mistake, an error. Look at the original Hammer core. In any case, core technology and design had advanced somewhat and they have increased the power of resin balls several times over.

Participation was already dropping rapidly 10 years before reactive resin was introduced. 

I think a little perspective is in order.  I started bowling in 1960 at the age of 12.  I started because a brand new 8 lane center was built in our small farm town of less than 1000 people.  That was the culmination of a construction boom that began in 1954 and resulted in no less than 9 new centers being built in the nearest city ( population 200k ).  The addition of all these new shiny centers with automatic pinsetters satisfied a pent up demand for more recreation in a population that was only a few years removed from WW2 and Korea.  Proprietors welcomed all these new people through the door and gave them a limited option to play the game unless they joined ABC sanctioned leagues.  This was a great model for both proprietors and customers most of whom were working in well paying union jobs ( look at the best bowling cities and they all have a major manufacturing base background ). 

The bowling industry over built by an possible measure.  The same think happened in Japan.  There was no way to maintain such a participation level on an organized basis, especially as other recreation options opened up that did not require nearly as much of a commitment over an 8 month period of time. 

Technology advances had a huge impact on the game, but not with respect to participation. 

I often find it funny that people blame high tech balls for ruining bowling, but nobody blames high tech drivers for ruining golf, which has also seen a reduction in participation in recent years.   

At the end of the day the surprising thing is not the decline in league bowling participation, but that it took as long as it did to occur given the boom or bust model that spawned the beginning of the modern game ( post 1950 ).

I know nothing about golf; so I can't blame anyone for the millions of wasted acres of grass and all the chemicals that have been used to maintain them.

I don't "blame" technology; I blame sociology (society) for not being able to keep up with technology. I do think (this is, after all, an opinion thread, not an evidence thread.) resin balls and their cores convinced a lot of mediocre bowlers they could score with the pros. Many believed they could make good money by turning leagues into gambling processes for their own profit. This I have seen. Many have quit just because there are not enough teams to provide them with significant earnings for their one night a week, if they finished in first place. This is not opinion; this, I have seen.

Many of the better bowlers have quit, not because of there are now many other things to do, not because bowling has gotten too expensive, not because tons of centers have closed because every other use for that property is more profitable than bowling for the owners. But because there were many mediocre bowlers coring as well or better than the previous skilled generation. Now, dedication and training and time spent practicing meant almost nothing. This, I have seen in person. This I know to be true.

Despite all this, I feel (I do not know!!!) that sanctioned league membership would be higher than it is now,without reactive resin. I think it will ever be as high as it was before. There are other sociological pressures which reduced the number of the membership before resin and even more after resin. That is my opinion; it is probably not a fact.

There is probably a hard core base of people who will always be looking for a league somewhere, no matter how many more centers close. No matter how Bowlmor tries to destroy leagues. What that base is, who knows?