Thank you ClioRS and Biomech for responding to my questions.
So if I understand it correctly the only way to lower the TEK POS difficulty is that we all collaborate and start combining all these small blocks into larger ones? And if no one (or not enough people) will do this then we'll never see a 40% monthly stake rate ever again?
That is correct. Due to relative complexity, I doubt everyone will merge blocks, so there will always be a fluctuating difficulty going forward. But I wouldn't worry too much about it and here's why:
The difficulty mechanism is intended to control inflation, which in the long run should boost the value of the coin. So in the end, regardless of how many coins you have, it may not make any difference in your total wealth.
Disclaimer: This is just a theory I pulled out of my butt.