The guiding principle can be found in our Constitution, which has a ban on "ex poste facto laws." You cannot, today, make what you did yesterday illegal.
Service change? I say "no". This is especially true of even older homes, where the circuits are sure not to be segregated in the manner they are today. A bedroom might be served by a different circuit for each outlet!
AFCI's? The places I do service changes generally don't even have ground wires! And four fuses seems typical.
When you do a service change, some circuits will have to be split off. In general, if I see two wires going to one fuse- two breakers are used. This applies even if the wires are joined with a wire-nit and pigtail to the fuse block.
But, really, consider all the requirements we've aded over the years. Would you also require adding bath GFCI's, kitchen convenience circuits, laundry circuits, outdoor receptacles, furnace outlets, smoke detector circuits, and ground wires part of every service change?
Adding an AFCI breaker might be a nice thing to do, but I don't consider it mandatory.
Heck- I just did a service change on my 1940, 30-amp service, two fuse home. Do you really think I gutted the place, adding all the stuff we now require?
Laundry? My main drain, according to the plumbing code, is too small for a washer. (Not that I have anywhere to put one).
Kitchen circuits? I have only the space atop my water heater for "counter top" area. The only receptacle is for the fridge, and the switch for the exhaust fan.
Bath GFCI? Where's the receptacle?
Furnace? Mine needs no electricity, and sits in the middle of the living room wall.
Outside receptacles? OK, I did indulge myself, and mounted one to the panel.
12 ft. rule? Nope- my living room has 50 ft. of wall space- and one receptacle (and that one is switched).
Smoke alarms? Put in a cheap ion-type anywhere, and you'll have nothing but nuisance alarms. This will result in most folks finding a way to disable the thing; they don't know there's another type (photoelectric).
My point is that it can be downright silly to try to apply today's rules to yesterday's work.
There may be an attitude that "more is better," or, "safety is good;" but things aren't always that simple.