It would be nice, but it's too high a bar to set, as the visa policies differ significantly between the three. There is a real danger the Schengen agreement it

It would be nice, but it's too high a bar to set, as the visa policies differ significantly between the three. There is a real danger the Schengen agreement itself will collapse in the upcoming years - Germany is already ignoring both the Schengen agreement and its own courts by keeping border controls.