W/o a picture I’m assuming you think the shelf itself will collapse but not the entertainment units? If that’s the case can’t you just add another piece of wood across the top of the bridge that spans the full length of the entertainment units to beef up the bridge portion itself?

3M80 2M22 6QS8 2M2 1EP500 Sony BDP-S590 Panny-7000 Onkyo-3007 Carada-134 Xbox Buttkicker AS-EQ1