My thoughts -

I wonder how much of the new train information is available in Lua script. I doubt it will change the operation of TSM much to be honest. It will change the threshold when a TSM starts to become an attractive proposition for a new base versus using the devs system. For example there is no way I could contemplate replacing TSM with this on my Seablock map where I have multiple different combinations of resources delivered to single platform city blocks into warehouses. But on the other hand, if your scenario is the same as the devs simplistic ore pickup and delivery example, the devs system will work reasonably well. Unfortunately, this also means that if you want to add TSM late in a playthrough having been relying on the devs system, this will be more difficult, as the dev system requires all the train stops to have the same name,, and TSM requires them all to be different names (although TSM automatically assigning a number makes this easy to do).
Issues with the dev system would be :
a) It would still result in favouring closer stations, though not as badly as before
b) It would exacerbate train shortages at more distant stations
c) Multiple resource platforms are not catered for at all
d) It still lacks any sort of prioritisation system
TSM of course solves all these issues, and provides infomation on shortages across your system.
Fundamentally, the dev system is a push from source system, and this is not changed.
TSM is a pull based on demand system which ultimately is manifestly better as points a) - d) are all easily resolved.