Who belongs to a Union anymore? -- Kerry in 2020?

Most Americans like labor unions, at least in the abstract. A majority (55%) holds a favorable view of unions, versus 33% who hold an unfavorable view, according to a Pew Research Center survey from earlier this year. For most of the past three decades that the Center has asked that question, in fact, Americans have viewed unions at least somewhat more favorably than unfavorably.  
Despite those fairly benign views, unionization rates in the United States have dwindled in recent decades (even though, in the past few years, the absolute number of union members has grown slightly). As of 2017, just 10.7% of all wage and salary workers were union members . . . 
Pew Research Center 

Belonging to a union is a fine thing, in abstract;

but if I were to join one my darn boss would have me sacked.

Or else the dues would levitate to heights I can't afford;

Teamsters pay enough that even Bill Gates would be floored.

My father was a Union man -- his father was one, too;

but all those heavy lifting jobs have gone to Katmandu. 

Former secretary of state John F. Kerry isn’t shutting the door to a second presidential bid, more than a decade after his narrow loss to President George W. Bush in 2004.  WaPo

Running to be President in 2020 is

something to give has-beens a fine calculating fizz.

But I don't think the prospects for a wannabe like Kerry

are anything to make Republicans feel very wary.