There's a few assumptions made on your logic which may not be true?
As the goal is to have as few detectors as possible, this implies no switch feedback. As such, if we have two trains sitting at a switch, then one crosses the switch into the next block, we have no clue which one it is. To make it worse, let's assume there's yet another switch and siding how do you setup Railcom and occupancy detection to figure it out?
We're depending on order of operations to figure things out.? Take the same switches and trains as before. Drive the diverging route train, close switch, then thru train follows first.
This may get reported as: switch closed, throat occupied (in reverse order of reality), pause, then both original tracks go unoccupied.
I see this all the time, as things are finicky, and none of the equipment is specced to be "real time".
No matter how you handle this situation at present - by additional sensors, I presume - you can do the same in the scheme I am proposing, except that maybe you cannot save those additional sensors.
All I am saying is that you may combine certain sensors watching mobile decoders, in order to reduce their number.
