In general for things like memory management and thermal management, if a handheld device is going to hit its limits, it'll do so well before the 30 minute mark.

Either your thermal solution can remove the heat of your CPU going at full power, or it can't. And if it can't it'll hit the limits in 5 minutes not 30 minutes, unless it's a huge water-cooling system or something like that.

The main exception here is batteries - but lots of fancy cameras offer things like battery grips for people who want to shoot for hours on end.