Well, for Free Comic Book Day, Midtown and DCBS and distribute DC's free comic with the rest of that week's DC's, but simply tell the retailers to wait until Free Comic Book Day to display them.
Remember, Free Comic Book Day is NOT on a Wednesday anyway. It's on the first SATURDAY in May, so ALL FCBD stuff is in the retailers back room before it gets displayed.
DC is leaving Diamond, but it's not leaving the comics industry or the direct sales channel. I am sure DC will continue to participate in FCBD. I also suspect that DC will continue to organize bookstore related events (like their previous Batman Day or Wonder Woman Day) and maybe distribute free stuff there as well.
Anyway, I agree that perhaps DC could have implemented this in a way that wasn't so shocking for retailers, but remember, DC and Marvel may be owned by multi billion dollar companies, but the publishing is NOT a billion dollar business for either DC or Marvel. As I posted above, DC's Gross Revenue for 2019's comics and GNs was about $60 million. That's gross revenue, not profit.
Diamond's announcement that they would be stopping payments to the publishers was likely just as shocking and unexpected as DC's recent announcement to Diamond was. Could DC have held out even if their profit were "only," say, $10 million? Sure, but I can see it being a real wake up call to DC that they can't continue to put all their eggs in that one Diamond basket. It's just not good business.
Now, why did they drop Diamond altogether instead of using Diamond as a third distribution company? That would seem to indicate that the relationship between DC and Diamond soured irrevocably as far as DC was concerned -- or maybe Diamond was trying to put pressure on DC to play ball and go back to being a Diamond exclusive. That's what I would want Rich Johnston to find out. There's lots more juicy stuff going on here than we know about right now.