The biggest problem for Training Day moving forward may be with the required suspension of disbelief.
Anybody who has ever watched a cop and/or legal drama may have a difficult time accepting that Frank and Co. are ever even a little bit successful with their methods of arresting criminals and gathering evidence.
There’s no way that most of what they do should stand up even in a fictional and corrupt court; Training Day may need to find a way to balance Frank’s method of fighting crime with actually putting bad guys away in non-lethal manners.
The shootouts and car chases and cinematic action sequences are great, but I have to argue that some of Frank’s most significant departures from law and order are just hard to believe.