I can think of a couple ways that this could be achieved, but none of them are within the osTicket framework. osTicket does not have a task scheduler.
You could write a script thats called by cron hourly that does what your describing (but of course someone would have to write it).
If I get a chance in the next few days maybe I'll code up a quick and dirty that ought to do what you're asking for. What ticket fields do you want in it?
ticket number - ticket priority - ticket opener name (ticket opener email) - ticket subject subject - date time opened - date time last staff reply
total tickets open: #