There will be plenty of others with Bs applying and some will get accepted. Don’t consider your hopes dashed. One grade doesn’t define you. A pattern does. AAMC has a grid divided by GPA for a reason and it doesn’t single out 4.0 as anything special.
Just try for As in everything else while still getting the hours in for ECs and shadowing, etc. Then study hard for the MCAT.
Here’s the grid. The top level is 3.79+. You can still make that with a B.