Since Yagrum had corprus disease, and the only man or mer known to have been cured was the Nevarine I kind of doubt he was still around. Fyr might have survived, and mer have been known to live to be 1000 either he or one of his "daughters" might still be around.
Fyr was over 4000 years old. He's far above and beyond the normal mer lifespan--which, by the way, is not nearly as great as 1000. Also, I believe Divayth Fyr administered the cure to Yagrum Bagarn after the successful cure of the Nerevarine.
Yagrum, on the other hand, seems to have regained much in the past. He still shows signs of corprus, but his memory seems to slowly be coming back from time to time. He spends quite a bit of time on his own now and wishes to remain alone. I am sure that glimpses of his past, coming freshly back to him, give him much to ponder over. I feel for my old friend. I only wish there was more I could do. A temper seems to rattle him every now and then and I have instructed my sister-wives to leave him be. In time, he will come to and understand what fate holds for him.
And interesting thing.... Yagrum confronted me after my arrival from the council, and wished to know if I still had the Tools in my possession. Upon hearing that the Hortator had taken leave and carried the items off with him, Yagrum seemed quite upset. What is going in that mind of my old friend's. I shall keep a close eye on him, for I worry about his well being.
- From http://www.imperial-library.info/content/sotha-sils-last-words
And, come on. The Last Living Dwarf, who is, by no coincidence, immortal and now regaining his memory
who also is anxious to get his hands on Kagrenac's Tools. To completely write him out of the story inconsequentially by Red Mountain exploding is one of the most foolish things a story-writer could do.
I say we haven't heard the last of Yagrum Bagarn.