There is a long article in current edition of German volleyball magazine. I will outline the most important informations and discussions here:
the discussion about a foreigner limit respective domestic player rule for the teams lasts already for 20 years or two decades now (!). When done the last time seriously, about 23% of the players of the first league teams (never including VCO teams of course, which are pure domestic education teams) were foreigners. This raised now to 49% (!) and shows, that there is a development to be discussed now more seriously.
Essentially all the womens clubs agreed, that they should introduce some kind of limitation. It seems even possible to agree on a certain approach: Stuttgarts Dutch captain Deborah van Daelen told them, in the first year they could prescribe always one domestic player has to be on court for every team and the following year two. This would of course result with the currently 10 professional teams in at least (maintaining the possibilty of substitutions) 2 Germans per team or 20 overall the league at the beginning and twice as much in the following year (4 per team required or 40 overall teams).
Interestingly this approach was not only kind of common view among the womens teams, but shared by Friedrichshafens Belgian ex-federal headcoach Vital Heynen. Regarding the extreme differences among the mens (!) clubs he stated, that we Germans should not try to find a perfect solution (there are many other proposals discussed), but take a rational and pragmatic approach like this instead.
It confirms, that additionally to the much higher differences in budget and strength in the men's league they often lack maturity (I think there are teams playing in the first league, which definitely shouldn't, because they are not really up to the task) compared to our women's league. But currently DVV and VBL are not willing to decide different rules for both, despite they are strictly seperated in this regard. IMHO they could introduce this mentioned approach in the first place here in women's league and wait, if the discussion in men's league settles in some way.
Because of a general education renewal approach DVV and VBL postponed in the meantime a decision and as expected such a rule will not come into power in season 2018/2019, but if at all earliest in 2019/2020. So we can expect at best a proposal at beginning of July 2018, nothing more.