I'm an amateur history buff, so a big factor I take into account when thinking about questions like this is context.
The Mosconi Cup has already shifted from its original purpose once. When originally created, the Mosconi Cup was designed to be an exhibition match similar to the Ryder Cup to introduce the European public to pool and the American stars, while also giving screen time to the Euros best billiards players, who also happened to be mostly snooker players.
Since those early days when America ran roughshod over the likes of O'Sullivan, White, and Davis, the Cup blossomed into a rivalry event. For a decade between 2000 and 2010, the west was treated to some highly compelling displays of pool and we watched Europe grow and get stronger. 9 ball pool took off, and with it other forms of pool as well became popular.
Then things began to go downhill. In 2011 and 2012 there were whispers and glimpses of Americans losing an edge, but excitement from 2009 was still high, and 2012 was especially close finishing at 11-9. All seemed well, until the next year. 2013, a year that will live in infamy (sorry, couldn't help it) was a three day stretch where five of Americas greatest legends in pool that had pounded Europe for much of the last decade got shellacked. America had lost cups before, but to lose 12-2, in Vegas, on the 20th anniversary of the cup? That was too much for a lot of people to take. Rumors and conspiracies began to fly that someone or a group of someones had fixed the event. Accusations were rampant, and while little was said publicly by anyone involved in that Cup, the landscape was already shifting under America's feet.
That Cup was a microcosm of the current state of pool in the US, and a glimpse into the future as a warning. Europe now had teeth, and American legends were losing ground. Many of them had been in so many cups, there was a question of who would replace them. To make matters worse, the hints of scandal never went away. Finger pointing and knee jerk reactions on the part of America and its players both professional and amateur began to become a regular part of the discussion. The landscape began to bring in new faces and people who had been successful in pool for years, but never to the level of an Archer or a Strickland. These were people like Mike Dechaine, Brandon Shuff, Justin Bergman, Skyler Woodward, and a few hold overs remained such as Shane Van Boening, Dennis Hatch, and Corey Deuel. In an attempt to find ethical leadership and experience, players like John Schmidt were included on teams to be emotional anchors, with some players like Rodney Morris being deemed too unstable and unpredictable to continue to serve as mentors for young players.
After 2013, the losses continued to mount, the gap in play grew wider, and the fun began to be sucked out of the MC for Americans. They were like a lion who has grown older and long in the tooth, watching another young lion come in and take away their territory and prestige. To make matters worse for the old lion, its own cubs were trying to come up in their own way, but the newcomers looked at and played the game differently than the graybeards, for better or worse. Ultimately, it has continued to be proven that either due to needing more time on the bigger stages of pool or simply due to a change in expectations for playing pool in America, its youngest and brightest stars have talent and confidence, but still are not ready to seriously challenge the best from around the globe in the new pool world their forebears helped create.
So, where does this leave America, the Mosconi Cup, and pool? Rest assured, the Mosconi Cup is far from done as long as the fans continue to show and the sponsors make money. Also, pool is far from dead and has more top quality players around the globe than at any other time in the game's history. And that trend shows no sign of slowing down. So what is over? To be frank, America's dominance of the game is over. We worked for years to spread the game we love, to build the field, sow the seeds for the love of our game, and build it into a world wide phenomenon. By doing so, we created the eventual generations that would dethrone us and take the game over, which we are currently seeing right before our eyes. America has fallen down a few pegs on the pool ladder.
This does not mean America is finished forever in pool, doomed to only have it has an amateur past time and hobby. What it does mean is America has a choice to make, collectively, both for non player and player alike. Either we embrace our new position in this sport and begin our steady climb back up the mountain through dedication, hard work, and a commitment to the game of pool the way that other countries have in the new pool world, or we will continue to slide down into oblivion until the day people begin to make a conscious effort to rebuild the game in America. It all depends how long we want the road back to be and how uphill.