You know, they adjust quite easily. My almost inlaws had always had an outdoor cat. He was a "good mouser" who spent most of his time outdoors. When they moved to a larger city, and into a condo, he had to convert to being indoors only. He loves it, he's turned into a total lap cat. He now loves to play with toys, spend more time with his humans, and demand that they cater to his every whim. I think the bigger adjustment was for his humans to get used to a litterbox.