Curious,

If you have a tooth above the space of #31 which would be tooth #2, and it's not occluding (biting) against your lower tooth #30, there is a good chance that #2 will drift down toward the open space of #31 simply because there is nothing holding it back. Which means that eventually #2 would have to be removed because it would become very loose and the roots would be exposed. The tooth would slowly avulse from the bone. Depending on the person, this may or may not take years to occur. Your dentist can tell you if #2 is occluding against #30.

Anytime a graft is done with the intent of an implant, it is best to not wait longer than one year to do the implant because the bone will start to recede because it has nothing to hold onto. The graft is done to encourage your own bone to grow and integrate with it as a means of filling up the holes where the roots of the tooth use to be. Without the graft, your own bone would fill in those holes as it collapsed inward from the sides of the holes. So the overall level of bone would be much less. Grafting does not add bone on top of bone.

Let us know how the second opinion goes!
Bryanna