Hello!

I agree with other coaches that you should be ready for anything (ofc, this doesn´t mean that you should not try to get previous cases -this for sure will help-, but don´t be sure that they will be repeated)

Written case interviews are indeed becoming very fashionable nowadays as a way to interview!

Remember that the skillset tested is the same than in the "usual" cases, hence, all the practice you may have done totally plays in your favor. 

One important point to add is the need to be very 80-20, structured and to the point, since the prep time is very short, so we need discipline with the analysis to have enaugh time to prep the communication strategy. 

There are many many entries in thsi same Q&A regarding written cases, hence, I would recommend you to look with the keywords "written case"

Hope it helps!

Cheers, 

Clara