If your alternator is not broken, then it should not really matter whether Murano alternators are on backorder or not. I used to drive a 97 Maxima and the alternator failed on that. It was long nightmare towing it from dealer to dealer until they had a part available. A few years after that, I received a recall notice - Nissan was recalling Maximas because of bad alternators. Well, I took my car in again and they noted I already had mine replaced.
So I guess the moral of the story is that Nissan takes a LONG time to fess up to any mass parts failures. Whether it is CVT or alternator, I would not bet a dime on a recall anytime soon if they turn out to be major problems. From what I have read, I think the Murano shares its alternator with other 3.5VQ powered Nissans. I would imagine the 110 amp alternator is also fitment on the Altima and Maxima.
On my Jeep Cherokee I had replaced the rotors twice then 4 years after I bought it, I get a recall notice for bad rotors. LOL! And that was a safety issue. They sent me the notice three times. Every time I chunked it. Speaking of alternators, I just replaced the alternator on my Cherokee (117,000 miles).
The Z also had a few reports of bad alternators and they also were on back order. But I don't think the number of problems I've seen on FA for MO alternators or the Z forums for Z alternators up to this point are sufficient to trigger a recall. There are always going to be a small percentage of failures for every item. And it's hard to tell with just posts. It's also a good idea if those who have problems will go to the knowledge base on this site and fill it out.
What's really interesting is the tire "feathering" problem on the Z. Now there is a problem deserving of a recall. 965 posts at one site in one thread with 38396 views...and still going. Nissan still doesn't have a permanent fix for it.