The issue with a film(s) of the HARRY POTTER play is that anyone sensible would want to sit on it until the cast of the film series (Daniel Radcliffe, et al) is old enough to do it. So, yes...they may be waiting 10 years for the actors to age into the roles.
The biggest issue with a DEH film is the opposite...zeitgeisty star Ben Platt is rapidly aging out of being able to pass for a high schooler, if he ever did. Certainly film would make that particular illusion harder to carry off. Does anyone want to see a film of DEH without Platt? Well...the stage musical is certainly chugging along without him, so...maybe?