The reason players have had to wait in turn based golf games in the past is because the games would not allow the non playing players to prepare for their shots until it was their turn to play. With good programming there is no reason that this needs to be the case and a turn based system could in fact be created that needs little or none of this waiting time by allowing all players to prepare their shots in the time the active player is preparing theirs. A simple picture in picture system could allow the active player to be viewed, and the non playing players could switch to a full screen if they wanted to by the press of a button. 
Something like that could indeed be a solution to the dead time the current turn-based system imposes on the players who are not 'up'. I don't stand behind my playing companions in real life and watch them rummage through their bag, consult their sky caddy, sort through their map and notes, while waiting for them to hit. I'm usually over near my ball, sizing up what I'm going to do. Once they'e hit their shot and it's done, I'm up and ready to fire on my shot because I'm already prepared to hit it.
Another twist on your idea might be to just have the game sense when the other player(s) are starting their actual swing and it automatically causes your golfer's "eyes" to pan over to watch the shot from wherever your golf is standing. It might interrupt what you're doing to some degree, but it wouldn't be anything that would affect your shot if the game was coded to prevent you from swing at your ball until your opponent's shot had come to rest.
Sixteen years ago, Jack Nicklaus 8: Golden Bear Challenge, had the best method of speeding up multiplayer play, without making the players feel rushed that I've ever seen in computer golf. They had a play option called "Ready Golf" (not "Ready Play"), in which both players would start on the first tee, hitting their shots at the same time. As soon as you were done watching your shot play out, you'd be taken to a virtual instant replay of your opponents shot. While you were watching their's, they'd be watching yours. You could fast-forward or skip to the finish of the virtual replay at your discretion to pick things up a bit more. The process would then repeat until both players were on the green, then it would revert to what we now know as turn based. It wound up reducing the the time required to play a multiplayer round by about 30 to 35%, and I never felt rushed. Text chat could be entered while your were watching the virtual instant replay.
I think your idea with the mini-camera that could be expanded on demand, or mine with the camera cutting to the view of the other golfer when they actually swing would be better than Jack 6's Ready Golf though. With either technique, it would carry the streamlined process out the finish, where even more time is spent studying a putt. Think about how much more it would speed up multiplayer play if you were sizing up your putt, while your opponent was sizing up theirs! The opportunities for greater efficiency and a more player centric focus here are plentiful, yet not at the cost of missing the full experience of what your opponent's are actually doing with their shots.
I say this after an excruciatingly long 9 hole team match play game I played in Perfect Golf last night. The host 'thought' he'd set it for nine holes, which I inquired about before joining the round. We got four people in the room and launched the round.
Forty five minutes later, we had played 7 holes and I was running out of time before I needed to check in for the night. The host figured out after the 5th hole that he had actually set it up for 18 holes. I was enjoying the actual action in the game, but it was frustrating with all the dead time. I realized then that something will have to be done to speed up play to make this play option work for me for the long haul.
