It all comes down to two things, what do they believe is in their best interest, and will the Middle East stay stable enough for their production to remain controlled as it currently is, or will someone break ranks trying for a quick profit?
Because in general terms their lifting costs are so small compared to the Shale producers in the USA the OPEC countries can easily set a target price and use the quarterly agreements on production to convince contract traders they are serious about that price whatever it is. If they set $60 or even $65/bbl as the price I think they can easily get it without overheating a new shale boom in the USA, and without much impact on crude demand. After all in the real world people were pumping nearly as much oil in 2014 and buying it all at $100/bbl for some time. It isn't as if a moderately higher price than the current level would be a shock to the system like it was back in 2006-07. Economically the OPEC countries want to get as much as they can for their crude without stifling demand growth or causing another USA fracking bubble like we got in 2014-15.
In truth another two or three years of world demand growth at recent rates and they will desire increased USA production because they will be able to pump flat out and still see prices going too high and set off another recession. Like any business they want to sell and recessions make that harder and less profitable. Since KSA declared they would defend market share in 2014 the OPEC nations have missed out on hundreds of billions of dollars they would have earned by reducing production and maintaining higher prices, but they could not see the future any better than I did in 2014. In 2014 I was thoroughly convinced of the red Queen problem for fracking and that the wells would be effectively dead after just five years. However it has turned out they have a very much longer tail after the initial three year production period than I believed, or that any of the doomsayers predicted they would have.
The debate now is to me the same as it was in 2013, how long until the USA runs out of places where fracking is worth doing? The second debatable item is, are there other new techniques ready to deploy after fracking peaks out that will get us another 15-20 years of growth the same way Fracking has done since 2009?