Not necessarily but it may be more prone to arthritis as it gets older.
It is essential to keep a cat like this at a healthy weight to reduce unnecessary extra strain on the back. Moderate exercise can keep the cat flexible and be sure that the cats favourite places are easy to access i.e put a stall or short step near to high places that your cat likes to go to, it will make access easier for the cat.
it doesn’t have to. They will have a harder time getting around as they get older obviously, but as long as you treat them well and make sure they have a comfortable environment they should live a long healthy life. This means making sure they don’t have to jump too high to get places. Make sure it has a bed on the floor it can easily crawl into.
it shouldnt