It is a troubled political time, but it may be premature to call it an end to the American Experiment. To begin with, while other societies have some advantages over the US, we have not seen mass migration from the US to other nations to enjoy the benefits you listed. In fact, today, migration to the US continues to be the direction of travel globally.
The US has a universal value; its called individual rights. The freedom to say and do you as you please, even if you are wrong or misdirected is the most fundamental universal value in the US.
This value, is exercised through two institutions which have stymied nearly all progress in the US; single issue interest groups and the US court system.
With well funded single issue interest groups, there is not only no reason to compromise, compromise threatens the very survival of the group and its funding.
These groups use the courts to stymie development and change in nearly every aspect of US society. Want to modernize infrastructure; the anti-development crowd will tie-up the initiative in the courts for as long as possible to delay or prevent the project from being started or completed. The courts interject themselves in every aspect of society and have become the tools of narrow interests which result in throwing sand in the gears of progress. To name a few; Immigration Ban, Keystone Pipeline, Abortion, etc.