Please, stop bringing up historical anecdotes as reasons why a tech union wouldn't work. It's funny how you don't bring up things like strong health care and training as anecdotes on the other side.
The question of whether or not there will be "union shops" or not is still yet to be seen. Whether or not there would be is a question of the union and the employers (i.e. TBD).
"with 46 employees voting in favor of the move and 37 opposing it".
https://www.nytimes.com/2020/02/18/technology/kickstarter-un...
Unions are also about leveraging power. While someone can try to start a union with any number of people, how much they can actually negotiate is going to hinge a lot on that number. Is 55% of the workforce enough to have significant leverage? I don't know and it depends on what the union wants. Would the union be able to reach an agreement with the employer that would force the others to join the union? That would seem like quite a stretch to me.