Let me comment if you want some specific future Opencv tutorial.. 

Future Opencv tutorials in progress

I have prepared some ML tutorials.

There is not to much complex tutorials like this on image samples.

• Rtrees random trees methods in opencv 3.1
• Boosting
• SVM 
• Testing of all cascades detect multiscales

Remarks: If cascade.detectMultiscale faild in opencv. Return 2 much values in vector<Rect> try use release of your sample instead of debug.. Works for me and I dont know why.. 

Also i would like to introduced

• Some basic KLT tracking
• KLT with feedback correction by NCC
• Basic MeanShift and CamShift tracking method
• Maybe some parts of Tracking learning detection method.. I will see. Maybe in many steps.

Video editing

•  Some drawing into video 
• Games with face detection 

Follow me and let me know if you want something soon 
Thanks for comments and likes