It is now c. $150 for crossgrade from Sonar. When do you expect they may ask for next money to stay current and how much it could be?

Version 3 shipped almost 2 years ago (Feb 2016). I expect v4 sometime late winter or early spring. I paid $100 to upgrade SO Pro from v2 to v3. Not bad every 2 years. And there were significant new features added with v3.1, v3.2, v3.3 and v3.5.
 
You will never be able to get SO Pro for a better price.

Afrodrum
It is now c. $150 for crossgrade from Sonar. When do you expect they may ask for next money to stay current and how much it could be?

At JRR you get S1 for US$125.

IIRC, v3 shipped in May of 2015, and PreSonus seems to be more on the ball with selling modular components not required to make Studio One function. One can only speculate on the v4 release date, but the pricing is more likely to follow the previous one (especially with the new customer influx).