I have a buddy who has the same thing. I don’t know much but he just skied Rodgers Pass and consistently climbs 5.12. I can’t give you recovery details or tips on conditioning. But the outlook is good!
To answer my own question, the only person I know of is Kelly Cordes. He claims his fusion doesn't slow him down much and has no problem climbing, even long routes in the mountains. He also does multi day ski expeditions. But I'm looking for one more opinion before I pull the trigger myself since its a long recovery and a "point of no return" procedure.
Check into ankle distraction arthroplasty instead of having an ankle fusion. I didn't want an ankle fusion in my late 40s, so I looked for alternatives. My foot and ankle trauma surgeon wasn't too familiar with the procedure and told me to have the ankle fused. I no longer go to that doctor. I had my procedure done at Hospital for Special Surgery in NYC 6 years ago and it has been a game changer for me. If you search the forums, you will find a few of us here on MP that have had good results with the procedure - it is not a sure thing, with a success rate in the 75-85% range. I am going to hike 30-40 miles this weekend and it won't be my ankle that holds me back.
Bit late to party, but I also have a fused ankle and largely agree with claty... It changes things, but it's still totally possible to climb hard. My ankle's been fused since I was 12 or so, so I never knew climbing without. I don't feel like I'm doing anything unique when I climb and my friends say I'm a "smooth" climber, but my beta is always different than other folks. I'm consistently able to handle low 12s sport and 11s trad though and the limiting factor is my brittle weaksauce fingers not my feet. High steps on my fused side are hard without calf muscle to generate force and I got my shoe stuck in a crack once and had to build an anchor and take off my shoe cause I couldn't twist my foot out, but for the most part it works alright.
Hikes are probably the more difficult part for me... It's just more jarring on your knees and my legs aren't as strong, so I'm sore after longer approaches/descents. Invest in good footwear, orthotic inserts, etc. and you'll be alright even if you aren't setting speed records. I dragged a 60lb pack up to the Bugaboos and still had energy to climb, but my climbing partner would've left me in the dust if he wanted. Like anything else, if it's something you want to do, you'll make it work.