I've been advocating true timekeeping for years to stamp out the time wasting as it drives me mad. I think I saw statistics the 'ball in play' time hovers around 68-70 minutes on average with some games dipping below 50 minutes. Timekeeping wouldn't stop the 'taking the ball to the corner' method of time wasting but my other rule change would. If a player is in the corner, the opposition get to kick them as much as they like without a foul being awarded
As for TV, they'd cope as they do with all other sports where game time in non-deterministic. Over time they would get to know that e.g. a 90 minute game would take 2.5 hours to complete. No different to today really where we often see 45+5 and 90+10 games.