Pendragon was pretty similar to running a module and that still felt like Rollplay. Having GM created settings and "campaigns" has worked well.
Whether they use a module or not, a system where the players have disposable characters would be really interesting to see. Old school adventures was quite compelling and much of it came from how players were normally in "pawn stance". The focus on the metagame and system mastery worked really well and as a viewer you learnt the game as the cast learnt it.
For many Rollplay shows the focus is on the characters, to the point that you can watch (or in some cases play) dozens of hours without really getting how the game works. Frankly, players not learning the rules is a staple of Rollplay I have come to expect and enjoy as a viewer.
By metagame I mean the game of players interacting with the mechanics as players, I do not mean metagaming the buzzword for having an argument with your friends because you aren't good at talking to each other