Probably close to none. The lifetime of the satellites is about 5 years give or take. According to this page [1], a total of 355 satellites have deorbited over the past roughly 5 years. That's an average of about 71 per year or about one every 5 days.
Since planned disposals are done over uninhabited areas (e.g. the pacific ocean), the likelihood of spotting one is very low.
Hope that helps answer your question, even it wasn't necessarily meant seriously :)
[1] https://starlinkinsider.com/starlink-launch-statistics/...which I suppose is closely related. The deorbiting satellite burns up because all that potential energy goes into heat because of the ~friction~ [edit: compression, thanks for the correction] that limits it to that low terminal velocity.
Put another way, every kilogram of Starlink spacecraft has as much energy "stored" in it's motion as around 4-5 tons of TNT.
Wow ... is it economical to replace the entire constellation every 5 years? How does the business side work? Or is it just a great money-burning party?
They also want to make Starlink satellites bigger, which also requires Starship's much larger diameter.
SpaceX says otherwise, see [1]
SpaceX spokesman James Gleeson, when asked about the 10 satellites, said SpaceX is “performing a controlled de-orbit of several first iteration Starlink satellites,” using onboard propulsion.
[1] https://spacenews.com/spacex-launches-fourth-batch-of-starli...
Now, none of this is an actual problem as they're entirely demisable, but the statement that they can achieve controlled de-orbit is false.
So if you control the orbit, you control the zone of re-entry. It's not a point or an oval in this case, but a "strip" a couple of kilometres wide. This is all that's required if the goal is to avoid major population centres.
This also means that the target is not "all over the world" as you put it - it's a very narrow, well defined stripe/trace (remember the scale we're talking about here!) and that's exactly what a controlled de-orbit is about.
This generally involves landing at a precise location of the Earth. It goes by a nickname, Point Nemo. A patch of ocean in the south pacific farthest away from any land. It's also far from standard shipping lanes. If you can't achieve this type of targeting it, definitionally, is not a controlled re-entry.
> It simply means aiming for a certain latitude by adjusting the orbit accordingly
You cannot aim a satellite for a "certain latitude" as orbits cannot follow lines of latitude. That's not how orbital dynamics work. I'm not quite sure what you meant to convey here.
> This also means that the target is not "all over the world" as you put it - it's a very narrow, well defined stripe/trace (remember the scale we're talking about here!) and that's exactly what a controlled de-orbit is about.
No it's all over the world, definitionally, because low earth orbits cross the entire planet as the Earth rotates. The possible locations the satellite can re-enter span a large portion of the globe from the negative to the positive latitude equivalent to the spacecraft's inclination.
I think you have a major misunderstanding yourself. If there's some term I'm using that you don't understand please let me know so I can help you.
Starlink satellites are pretty well aerodynamically balanced when in their "ducked" orientation, but are not going to be able to overcome aerodynamic torques below 200 km or so, meaning they will be unable to point their thrusters in target directions. At that point, there are still 1-2 days before reentry will occur. Hour-to-hour variability in tropospheric atmospheric density due to solar flux levels and geomagnetic activity means that the precise reentry time will be unpredictable to within a few hours (which equates to anywhere along the ground track of a few orbits).