"because they were the team beating everyone in 4th and 5th grade and have been playing together since then."
This statement is absolutely inaccurate with respect to the 2014 and 2015 Express teams. Those teams did not come together until the 7th or 8th grade. For the record, the 2014 team has 14 players committed to Div 1 schools. The 2015 Express Orange team just won the U15 national championship and is easily one of the top 3 or 4 2015 teams in the US. You really don't know what you are talking about. Nevertheless, enjoy your son's 5th grade team.
This is what will happen. If the superstars of today's 5th grade are still the superstars in 8th grade they will be individually "invited" to play as a "temporary" team in a tournament after the regular summer circuit is finished. The kids and the parents will feel flattered about being invited to this "all star" team, the hard sell about recruiting will be made and presto - you have the new 9th grade Express Orange. Happens every year now.
