Thank you for your question and welcome to Just Answer.
Well, if you could guarantee that your tooth would just eventually fall out, then there would be no serious consequence of waiting for that to happen. However, what is really happening is that your tooth is decaying slowly and growing closer to the nerve of the tooth. Having had a crown, your tooth was shaved back on all 4 sides to accommodate the size of the crown, thereby exposing the inner layer of tooth structure (the dentin). Now that your crown has been off for all this time, areas on the dentin layer have begun to decay, causing parts of it to chip and flake off. The pain you are starting to experience will get worse as the nerve f the tooth is slowly invaded by the decay, until you have a full fledged toothache. Chances are this tooth is now beyond repair and you should make an appointment now to have a dentist evaluate the situation and have it removed now (if needed), while it is still a relatively easy procedure, rather than waiting until you are in too much pain and discomfort, and the extraction becomes more difficult.
I hope this answers your question. If you would like to discuss this further or have any additional questions, please reply to my answer and I will get right back to you.
Sincerely, XXXXX XXXXX DDS
Thanks for that additional information. That changes my answer slightly. You still have the advancing decay from the exposed dentin layer but you will not get the classic toothache as it advances toward the center of the tooth. You will have some discomfort as the decay does also irritate the gum tissue. ALso, you will continue to experience bits and pieces of the biting portion of the tooth coming out as the decay deepens. However the entire tooth will not eventually come out. You will eventually be left with just the roots of the tooth lodged in the gum and bone. At this stage, chances are that you will have no discomfort from these roots but in some people, the these do get infected and have to eventually come out. BotXXXXX XXXXXne, the presence of the root canal will prevent this from becoming an acute situation for a lot longer time than if you had not had the root canal. From a health standpoint, you should consider just having the whole thing removed and prevent any kind of infection from developing. I hope this helps.