A Crown Heights landmark is still in danger of falling apart and a proposal to save it met with concern, but not approval, from the Landmarks Preservation Commission on Tuesday. The landmark in question is the George B. and Susan Elkins House at 1375 Dean Street. The current owner wants to convert the single-family structure to a four-family home, add glass enclosures on the sides, add skylights, change the attic, excavate in the cellar to give a higher ceiling height, and put on a glassy rear addition. It was the glass enclosures that really didn’t sit well with the commissioners.