I'm nearly finished this at mine. The works weren't specifically for future proofing, but builder suggested some great things.
I had no d/s loo, so that was a priority. Not much room in my little house, but builder came up with a great reconfigure so I now have a d/s shower room, and the washing machine fits there too. I didn't fit the shower as it was over my budget but it is wired and plumbed for one if needed in the future. I will get more use from a baby utility room with loo for now anyway!
Got switches at chest height. Got new loos in the "comfort height" range, it is a tad higher than normal loo, but my god it makes such a difference getting on and off the throne!
Drawers galore in the new kitchen, so much easier to reach and find things. Overhead cupboards are for seldom used items.
Got a rail on both sides of the stairs. That is so good especially for coming down.
I got rid of the bath, and got a walk in shower (not a wet room) upstairs. Inset shelf in the shower stall is fab. No more things dangling around the shower head. A n LED lighted mirror is great for plucking those goddam whiskers, and it has a demister so it doesn't steam up. Grab rails and a fold up seat in the shower.
Very pleased with it all. I am 66 and live alone, and touch wood am ok at the moment. But we never know. I can use space downstairs to sleep if necessary, but not needed right now.