This might be a bit long, but I need some objective perspectives. Since horse and riders are seniors, I think this is the best place for this post. Seniors are going to have a different perspective

Fast forward to now...Louise and I have been happily leasing Ranger. He has gotten back into shape, looks great, and we are starting to work on canter. This morning, the BO told me that the owner might sell Ranger if I don't continue the lease. My main question is how much is it fair to expect from a 26 yr. old horse? Would it be okay to show him lower levels? How about trailering? I take lessons 4 hrs. away (there is a horse available there) and clinic 2x/yr. 5 hrs. away (again, there is a horse there). Personally, I think that is too far to trailer an older horse. I think if I could show Ranger locally at lower levels, I would be happy. I would miss taking him to the clinics and the opportunity to learn on him, but being able to look forward to my rides, like I do now, is worth a lot.
Ranger has been absolutely wonderful. Neither of us ever worry when we are on this guy. I find myself perfectly confident in situations where I would probably have dismounted (my m.o. when I get nervous). Louise and I love Ranger. We were both in tears at the prospect of someone else buying him. He is the sweetest horse; we can put our granddaughters (5 and 9) on him.
One of my concerns is what happens if he becomes permanently unrideable? The BO where my retired horse is boarded commented that if Ranger has stayed sound for 26 years, that ought to say something. I know, as do we all, that nothing is guaranteed with horses. If I bought another horse, I could walk out the day after I signed the check, and something could have happened to him to render him unrideable. If Ranger was my only horse, I wouldn't care, but I am already paying board on another retired horse. Louise has land at her house and said she would fence it, and we could retire Ranger there when the time came.
Ranger wears bar shoes on front, and it was implied that he was navicular. In the course of discussions today, it was revealed that Ranger had xrays taken a few years ago, and while he was never formally diagnosed with navicular, since he needs the barred shoes to stay sound, it was decided that navicular must be the reason. However, I don't think that Ranger has, for the most part, ever had particularly good farrier work done.
This is what I am thinking of doing...taking Ranger to a good vet, having his feet xrayed and finding out exactly what is going on with his feet. In my mind, at this point, if he isn't navicular, then I think that might sway me to look on taking him more favorably. I'm also thinking of consulting with a vet about what is a reasonable amount of work for us to expect from Ranger. I just want to see what you guys think. Opine away

Update: Well, after a lot of drama on purchase price, Louise and I bought Ranger. After looking at some other prospects, I just couldn't ignore the voice in my head to "Buy Ranger!" It is working out great. I decided that while we have this time with Ranger, I will be putting money aside so, when the time comes, I can buy another horse. In the meantime, I am doing what I want to do. I took him to a local trainer's barn for Ranger's and my first lesson together off property. He was perfect. I was able to load him completely by myself, and he didn't take a step out of place. I'm hoping to be able to do this all winter (at least 1X week), but I will have to see if I can change my work schedule. All totalled, from load to unload at home, it was almost a six hour event. Thanks for all the words of wisdom! I will post some pictures soon.