Is the caliper comes lose while driving, your risk is that it jams in the wheel barrel. That'll either destroy the wheel, or possibly even lock up the tire.

It's not great. If I had to get the car rolling, I'd cap the brake line and remove the caliper entirely.

__________________
2011 M3
2006 Sierra 2500HD 4WD LBZ/Allison
2004 X5 3.0i 6MT
1995 M3 S50B32
1990 325is
1989 M3 S54B32

Hers:
1989 325iX
1996 911 Turbo