How much stronger could the storm get?  The picture below shows the intensifying storm that we just analyzed.

10 mb more air is leaving the column than is being added.  The surface pressure will decrease and the storm will intensify.
The picture below shows the stronger storm.

Note the surface pressure has dropped from 960 mb to 950 mb.  Note also the increase in the amount of surface convergence (if the surface pressure is lower, the winds will blow faster and carry more air in toward the center of low pressure).

Now more air is being added to the storm than is being removed.  This will increase the surface pressure somewhat and weaken the storm a little bit.  If the surface pressure were to end up around 955 mb and the 4 arrows representing surface winds were to each add 12.5 mb worth of air to the column, everything will be in balance.  The storm wouldn't strengthen or weaken.