Even if you're alive to push it, the GA autoland system that I know of puts you over the threshold of a nearby airport (if possible) at 5' AGL. After that, it's up to the occupants. If there's nobody who can land, it's probably off the runway.
Oh, but it's for experimental aircraft only.
The certified system that's in use on the Vision jet, TBM, Piper M-Series, and coming to several other turboprops and small jets soon, does in fact fully land the aircraft. It will land, come to a complete stop, and shut off the engine(s). Gonna have to get a tug to get off the runway though.
Cool, that's about 1000 aircraft that can do it. It's a start
The autoland first came out in 2021. I would expect that by 2035, likely before, there will be a retrofit option available, given the general timeline of how Garmin's stuff starts out on the high end and trickles down to the GA retrofit market. It'll be horrendously expensive the first few years and then get better.
It does require some hefty hardware, though. Currently, it requires the second-gen G3000 hardware, a radar altimeter (for the flare), autothrottle, wheel brake actuators, and a fuel shutoff that's basically a solenoid that pinches off the fuel line. (I have not seen this myself, but that's how it was described to me.)
I would be really surprised if the first piston aircraft to have this wasn't the SR22. I'd also be really surprised if this took longer than another couple of years to implement as factory equipment in the SR22. I'd bet you see autothrottle by #OSH26 and autoland by #OSH27 unless they decide to introduce those as part of a new "G". They're on the SR22G7 now, so maybe they'll do autothrottle on the G8 and autoland on the G9.
To get this into your average GA aircraft as a retrofit, we'll need some hefty processing power (higher-end glass), surely a Garmin autopilot, and autothrottle. We'll probably need brake actuators. We might need the radar altimeter. The fuel-line pincher will probably be optional, as you can have the screens tell the pax to pull the red knob before they go and kiss the ground. Maybe. It's possible they'll decide that the chance of someone missing that step and getting chopped by a prop is too great, but the fuel-line pincher is probably the cheapest part of the whole mess.
I would expect, as with the more expensive birds, that you'll see the autothrottle first. This will be a challenge for those of us with vernier throttle controls.
It'll also be pretty stupidly expensive. I would guess that this will appear once Garmin comes out with whatever replaces the G500 TXi; that unit should be capable of not only driving the GFC500 system but also adding another servo and a different mode controller to add the AT button, plus an AT DISC on or very near the throttle lever. Garmin EIS will be required as well, of course.
Once the autothrottle part is tackled, it'll be on to full autoland. There was only a very short time between those systems appearing on the aforementioned aircraft, less than a year IIRC. At that point, you'll probably be able to add all of the extras provided you already bought the new hotness.
BTW, there's currently a Garmin radar altimeter that you can put on a G500 for the low, low price of $7500 plus installation.
I will say, it's a helluva system. Not only do you get the Big Red Button on the glareshield, there are two additional scenarios in which it activates itself: 1, you hit the LVL button after a spatial disorientation event and then do not deactivate LVL mode and return to flying the airplane for more than two minutes. 2, cabin altitude exceeds 10,000 feet and pilots don't make any inputs or respond to prompts. No matter how it's activated, it broadcasts its intentions on ATC, guard, and CTAF frequencies as appropriate, blanks out the screens and begins providing information for non-pilot passengers instructing them to buckle up and telling them where it's going to land and in how much time. Quite slick, and it will definitely help sell airplanes.
