Poor chances... since last episodes these are fillers and they made they own end of season, I don't think they will make another season...
Second if they had doing the second series in plans, we will know it, before ending of first season...
there will be lots of stuff hasn't been uncovered yet like: why did jack say "This is the last time we can play together" What happend to him? and break (or idk what his real name is) said: "I Still haven't told you everything"
Some anime are being created only for in order to make the audience interested in reaching for the manga... If would like to create second series why did the last stretches not according to the manga up till now did hold on to original events? Ps. It not so I don't want the second series, but I don't want to get my hopes up more deceptively, that there will be the second series.