Bakasana or crow pose can be quite daunting for many people-I will sometimes offer the option of putting a blanket or cushion on the floor in front of you, to give the illusion of the floor being closer ( and remove some of the fear of falling)...as with any prop you will have to let go of it at some point & in my experience once a student has felt the where the balance is, and what needs to be engaged ( shoulders, bandhas etc) they are happy to remove the prop.