How long can dental post & crown last?

I was treated with veneer after root canal therapy 4 months ago. During regular check up with my dentist(who did not put the veneer) raised his concern that due to removal of my teeth during veneer attachment, it may not be possible to get crown without the post. In my understanding, post is one of the final dental treatment I can get before implant. Kindly advise, if I keep good hygine of my teeth, rougly how long will I be able to maintain the post?