I think its rather difficult to predict the intensity since the water is really warm. I always thought it would be a two but not sure about a three. If the forward speed keeps as fast as it is forecast to that will be a big help in limiting the damage.
Definitely difficult to predict intensity. Idalia will pass through the super-warm loop current. If the storm intensifies into 3/4 once in the GOM (a la Charley and Ian), it will be too late at that point for mass evacuations in the Tampa Bay area.