Recap
The Boston and Philadelphia franchises joined the American Association after the Players' League folded, and both folded together with the AA after the 1891 season. The PL franchises in Brooklyn, New York, Chicago and Pittsburgh each merged with their National League counterparts after the 1890 season.
Although the league was started by the players themselves, essentially as an elaborate job-action to improve their lot, the venture proved to be a setback for them in the longer term. The infamous reserve clause remained intact, and would remain thus for the next 85 years or so. The already-shaky AA had been further weakened by the presence of the PL. The Lou Bierbauer incident, in which the Pittsburgh Alleghenys signed Bierbauer over the objections of the AA's Philadelphia Athletics, the team he had played with before joining the Players' League, caused a schism between the NL and the AA, and the AA failed a year later, reducing the total number of major league teams (and players), giving the remaining owners much greater leverage against the players.
One benefit of the league, from the management standpoint, was the construction of new facilities, several of which were used for a while by the established major league clubs. The most prominent of these was a new Polo Grounds, originally constructed as Brotherhood Park for the New York Giants of the Players League. Afterwards it became the home of the National League's New York Giants from 1891 to 1957 (it was rebuilt in steel and concrete in 1911) and of the New York Mets in their first two seasons. It was also the site of many other famous sporting events through its 75 years of existence.
I sincerely appreciate the research work, and the information being shared. It is important and interesting history.