Could card check have saved US unions?

Suppose we had card check back in the 50s – would that have reversed US labor union history – would we likely have fully representative union density today, instead of 6.2% in the private (non gov) economy?

Starting out with 35% membership in the mid 50, card check wouldn't have led to a lot more unions – simply because we could organize pretty successfully without card check back then.  Came the years of (illegal) escalating anti-union blow back, card check could not have helped holding on to unions we already had.  

Came the years of fierce (illegal) management opposition, card check wouldn’t have been any more of a magic organizing bullet than it would be now.  Easier to form a union in the 50s without card check, than to organize now with card check; impossible in most cases.

At the very most: if we had card check starting in the 50s, union density might level off at a somewhat higher level these days (starting out with a few more unions) – assuming density ever stops going down.  Might card check today send density climbing way back to 50s levels or anything like it?  Good luck.

Only one way back:
https://onlabor.org/why-not-hold-union-representation-elections-on-a-regular-schedule/
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EITC transfers 2% of income while 40% of our workforce earns less that what we think the minimum wage should be ($70 billion out of $13 trillion of income — wages are 2/3 of GDP).

We cannot set a minimum wage any higher than the wage that the unionized workers with the weakest bargaining position could negotiate for themselves ($15?). (The current $7.25 federal minimum wage is at the 1956 level, inflation adjusted.)

Perhaps, once we contemplate every other avenue to rehabilitating the US labor market to likely be unfruitful, Andrew Strom’s proposal of regularly scheduled cert/recert/decert elections at every private (non gov) workplace may finally seem as inevitable as in due course it must be.