Forward-looking floor plan design upper floor

Hi hello,
my husband, I, and our two sons currently live in a 100-year-old house. Together with his grandmother and her caregiver. As soon as the grandmother is allowed to leave this world (she will soon be 99 years old) we plan to demolish the old, very large house to then build a single-family house (pictures 1,2,3). (The furniture in the pictures will of course not stand exactly like that.)
We live in a perfect location for us in a small town on the beautiful main street. Here we have a corner plot and a large garden on the south side. (Picture 4) That means you are quickly in the middle of things on the north side and yet have peace in the garden.
The new house must be flush with both streets and the building style is closed. (Picture 5 shows the plot with the current house.) That means the garage (or in our case, contrary to the drawing, it will be a carport) must border the neighbor.
We have spent a long time working on the floor plan. And apart from some small changes, like shifting some doors etc., the house will probably be built like this because it meets our requirements :) The house now has just under 180 sqm. And we are building it for our family of four. The youngest just turned one. Nevertheless, I am concerned about the question of what will happen in 20-25 years when both children have left the house and the house is far too big for 2 people. In other words, I am looking for a way to downsize if this is actually desired then.
The staircase must remain in the middle because I don’t want to have to go through the entrance area to get to the living area. This is also an urgent wish of my husband. Upstairs we plan a nice reading area in the hallway, which thereby serves as living space and not just traffic area. Similar, only bigger, we have it now. Both floors should have a connection through the staircase. What I don’t want later is to say we live on the ground floor and the upper floor is completely rented out, because on the one hand, I don’t want to hear a stranger stomping above me in the living area (it doesn’t matter to me in the utility room and toilet) and on the other hand, there is our garden and I don’t want the tenants to look into our garden. Therefore, I thought of the following layout for later.
(Picture 6) From the flight of stairs with landing, there would be two straight stairs. The door from the utility room will be raised a bit more and would thus be the tenant’s entrance door.
I am rather thinking of renting office space/commercial space, as all windows face north. The layout is rather unfavorable for a one-room apartment. However, you will only see what makes sense when the time comes; we can’t plan and foresee that far ahead. (Currently, facilities for a massage practice have been rented out in this location (but on the ground floor) for about 3 years by my husband’s grandmother; before that about 10 years there was a video rental store.) The important thing is that we then have two completely self-contained units with separate areas and that with as little effort as possible!

What do you think? Who has other ideas?
Who has ideas for the laundry chute (which I don’t like where it is anyway)?
I am happy to receive suggestions, except that I don’t want to separate the south area upstairs from our living area, especially since our bedroom will be there then.
Thanks a lot in advance
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Nevertheless, I am concerned about what will happen in 20-25 years when both children have left the house and the house is much too big for 2 people. In other words, I am looking for a way to downsize if that is actually desired then.

Want an honest and straightforward answer? Deal with it in 20-25 years. Build the house the way you need it now. A lot can happen in 25 years.

The podium staircase would become two straight staircases. The door of the utility room will be set a bit higher. And would thus be the entrance door for the tenant.

At this point, you lost me mentally.

What does the term "Wohndiele" mean?, after all, almost 13 sqm and quite little usable space. The hallway past the stairs feels very cramped or almost a tripping hazard; the same applies upstairs at this point. The dressing room therefore already massively interferes with the floor plan. Provided the furniture size is correct, the arrangement with the dining table and the couch probably won't work well. It seems as if you first have to get past the stairs and then overcome the obstacle course of dining table/kitchen/living area to finally get to the nice outdoor area. In short, in my opinion, it is too tight! Why have guest rooms both downstairs AND upstairs, that could free up space for other necessary areas. How do you get daylight to the stairs; because of the unnecessary projection of the stairs, they stand in the middle of the house... all because of the dressing room? The huge opening at the terrace could cause various problems or put considerable strain on your wallet. Did an architect or planner draw this? Upstairs, as said, stairs!!!! A gallery is basically possible but not if I had to restrict the living space and stairs so much downstairs for it. What you are planning might largely be feasible, although you never know what will happen or come (see grandma...) I would definitely implement something like that with an architect. For example, at the time we converted the garage in the house/ground floor into an office, it was planned differently…

At this point, you lost me mentally.

True, it is expressed a bit strangely I mean, of course, to displace in the floor plan. And yes, two new, straight-running stairs would then be needed.

That's right, it's expressed a bit strangely. I mean, of course, to shift in the floor plan. And yes, then you would need two new, straight-running stairs.

And I still don't understand anything, even though my partner says to me: "You are not at all a little fool" ;-)