I will answer you from the point of view of someone who hasn't been there but has been able to witness the testimony of many moms that have been there. Hopefully a cosleeping mom will jump in here too.
When does it end? whenever you put an end to it. Beleive me, little one will be happy to stay at your cozy bed FOREVER. It's up to you to decide what's best for your family. You have a wide range of options: from stopping cold turkey the nursing and the co-sleeping, or stopping cold turkey the nursing but keep on the co-sleeping, or stopping cold turkey the nursing and gradually move your baby to a crib or toddler bed (whatever your choice is)... as for sleeping, you can choose. The nursing at night can also be gradually limited to 2 takes at night, say and deal with pat/shsh or pu/pd the aditional wakings.
At your baby's age I'm pretty sure he's taking enough calories during the day (is he on solids?) and the wakings are more a comfort/habit thing than a real need for calories/hunger. There are ways to stop the wakings for nursing in the middle of the night. I'm not sure if you're posting for advice on how to do this or just to know if there's a chance that this will fade into toddlerhood. For what i've seen in this forum i can tell you that NO, i'm afraid it recquires a lot of work and commitment on your side and your partner's side. There will be sleepless nights and there will be tears on both sides, but it's not as ugly as we fear sometimes and i can guarantee you it's totally worth it. We all deserve a full night's sleep. And we feel so human after one!
Let me know if you need advice on how to get started. We will be here for you through the process, whatever you choose.
Good luck and keep us posted!