I saw this thread last week and I made a mental note to chime in. I'm younger than most on this forum (38), but I have older parents. My father was born in '31, my mother in '35. This will be a long story, but I think it's important to make my point.
They built the house I was born/grew up in in 1969. It was their dream home. A big, sprawling ranch on a bit over an acre on the local public golf course. My mother was in the garden club, so it was extensively landscaped. I was very fortunate to get to live in it as a kid.
Fast-forward a few years and my parents were getting into their 70's, but they were in great health. My father golfed six days a week and my mother spent a couple hours a day tending flowerbeds. Still, my mother started to get worried about the upkeep of the big house (2500 sq. ft. on the main floor and a full basement) and the accessibility issues. See, even though it was a ranch, the laundry/sewing room was in the basement (and the stairs to the basement had a short-run, so they could be treacherous). The master suite had a bathroom, but it had a tub, not a walk-in shower. The house had an attached garage, but you had to go up a flight of stairs to the front porch (outside) to get into the house. There was no way to get into or out of the house without at least five steps. There was a sump in the basement, so they had to make sure to run a generator any time they lost power to keep the basement from flooding. On top of that, it was just a ton of square feet for my mother to keep clean, thousands of square feet of flowerbeds requiring hundreds of hours a year of work to keep up, a relatively big lawn to keep mowed, and a very long drive to keep cleared.
My father tried to placate my mother by telling her that, when the time came, they could turn one of the upstairs bedrooms into a main-floor laundry. They could have the bathroom remodeled to include a walk-in shower. They could get a proper generator wired-up. He put her off for a few years, clearly getting frustrated when she brought up wanting to move into town. I think that, for my father, that house was what he had to show for all his hard work and the years he scrimped/saved/sacrificed to raise six kids on a modest salary. I never thought of Dad as a sentimental guy, but I think he was too attached to let it go.
Finally in about 2009-2010, my father started to see that they weren't taking as good care of the house as they always had. It just gets harder when you get older, I suppose. The house was going to need a lot of work in the next several years, just when they didn't want to be doing it. On top of that, most of the required remodeling would be expensive and the layout of the house often meant that the result wouldn't be ideal.
So my father finally (begrudgingly) conceded and they (well, my Mom...) started to look for a new home in town. Then, just before the 4th of July in 2011, my father had a stroke. He lived just long enough for his six children to get into town to say our goodbyes.
Now my elderly Mother was faced with being alone, four miles outside of town, in an older house that was way too big for her to take care of by herself. The closer children (I'm about the closest at around a 3 hour drive) tried to make sure that someone was there every weekend to help. My brothers and I pitched in to take care of the finances (Dad did all that), mow the lawn, change furnace filters, fix leaky faucets, and on and on. It was very hard to have someone there every week (and my Dad used to mow twice a week!), so eventually we hired help to take care of the lawn and clear the drive. Still, my mother would talk about how hard it was for her to keep up with the weeding or to vacuum that much space, etc. In late 2011, she fell at the bottom of the steps down from the front porch, tore up her face, and broke a tooth. That was the final straw.
It took us quite awhile, but in 2012 we got her house sold and moved her into a 3BR, 2BA condo with a 1-car garage in town. Everything is on one level (the condo is a duplex on a crawl-space), the master bath has a walk-in shower, etc.
It was incredibly hard for my mother to downsize. She'd spent 43 years filling every nook and cranny in that house and it showed! It broke my heart to see her struggling to decide which of her precious collectibles she'd take with her and which had to go. I was as understanding as I could be, but we had a deadline for the move and a very finite amount of space to move into. I'd ask her which (of the >50!) tea kettles she wanted to keep and she'd look shocked and say, "All of them!" Then I'd explain that all those tea kettles would fill every cabinet at the condo and she'd have no room for dishes. My sister (supervising from a thousand miles away...) would call me and yell at me for being mean to her by telling her she had to get rid of stuff. It was horrible, and I am certain it would have gone better if she'd had my Father there to lean on.
Then, the first winter she was in the new condo she was trying to shovel the front walk (despite having someone to do that for her...), slipped on the ice, and broke her hip. Had that happened in the old house, she might have died of exposure. Thankfully, one of her neighbors in the condo development saw her fall and she got help right away. The recovery was a bit slow (and she's still not back to 100% of where she was before she fell), but she was able to take care of herself much sooner thanks to the fully-accessible condo. It would have been months before she could have lived in a home that required steps and didn't have a walk-in shower.
Since then, my brothers and I put in hardwood flooring in the bedrooms, remodeled both bathrooms with heated tile, put in custom closets, remodeled the kitchen with tile throughout, granite counters and new appliances with her needs in mind and had the entire place painted. My mother LOVES her new community. She spends all day gossipping in turn with all the other retirees in the condos up and down her road. She'll have one neighbor over for tea, then another for wine, then her bridge group over to play cards and have snacks. She's probably as busy as I am! She's a very short drive to church and the stores in town. We were watching her withdraw and fade-away at the old house, and she's really thriving in her new life at the condo.
So please, please start thinking about your future sooner than later. Eddie is right. Don't mess around trying to make your old house work because of your sentimental attachment to it. Figure out what you should have, don't make any compromises, and do it! If your wife wants to move somewhere warmer, you may want to just keep your current home up for a few more years while you take care of your mother and then move. But if your long-term plan is to stay in town, or if your budget would allow two moves, then now is the time! Don't wait, because you may not have the luxury of time you think you do!