I doubt that, the in-game info clearly states, that for getting into Platinum Division you get 100T.
When you stay at same division the reward is less, but we have no clue what will be in platinum.
Of course if it was to get 100T every month if you stay, ok it is tempting :P
But Nordeus historically shows that i wont be close to that :P
Yes this is fact, but you wont need to move up as there is no move up.
If you are at 1000+ you remain at the same Division.
If you get around 1200, next season you will be at 960, so reaching 1000 will be easy.
So you will always aim to finish your season around 1200+.
So as you said around 200 points each season. Doable. First 3 positions get extra points