
Realistically, how many more volumes/how long do you think this manga will continue until we see some sort of resolution/significant development?

Probably 100 volumes or more given the amount of things that still need to be resolved. That's if it ever gets finished. Sometimes long manga like this end up never finishing. Like detective Conan, glass mask, nana, and berserk.

honestly, it'll probably be 5 novels or less. The mom issue is pretty much resolved, this will likely be the last character she creates, I wouldn't be surprised if Ren figures out how to get in the same drama as her so they can work together. Regardless, it's definitely started its final arc.
I wonder if he'll be nicer to him when he realizes why Kyon fell in love with him in the first place.