It wasn't DLR drivers striking today, and you will notice this strike had much less of an effect than recent tube strikes.
But your post does actually make a good point, get unions out of a position of power to disrupt essential services altogether.
The majority of this thread has been about drivers striking, and the comparisons made towards driverless systems and the idea that getting rid of drivers will somehow make everything hunky dory.
My point, and has been throughout, is that getting rid of drivers makes little difference if the people controlling the service are prepared to walk out en masse. Hence my mention of the DLR strike.
Removing unions from a strong position is a difficult fight, and one that will no doubt cause more disruption, and probably on a much larger scale than your average 24/48/72 hour strike.
It might happen, either through the passage of time where the more militant members slowly move on and retire and the newer members are not as active. From personal experience, I can't see that.
The other way is if someone decides to put up a fight and force a change though and ban striking. I certainly wouldn't want to rely on the Underground on that day.