At least in recent years, MacArthur has also been in the habit of taking a couple of months off in the summer. I think it is usually in July and August. I started watching their services here and there 2-3 years ago, mostly in the evening. While he did preach some in the evenings, other men may have preached close to half the time.
Based on recent posts on his FB, Phil Johnson is 64 years old. (I hadn't thought he was that old. But he just celebrated his 39th wedding anniversary, so it does make sense.) He's also never been a pastor other than pastoring his fellowship or whatever they call it there. (Those groups also have preaching that is recorded, etc.) He runs the radio ministry, Grace to You. (Before that, he ran Chuck Swindoll's radio ministry for a few years.) If I recall correctly he never even preached from the pulpit there until about 10 years ago. (I seem to remember him saying that when preaching a message at the Shepherd's Conference in 2009.) I think he has said that he hopes that he does not outlive MacArthur. People used to speculate that it might be Steve Lawson, but I'm guessing he is also probably about 60 as well. I suspect they would probably go with someone younger and someone that is already known to the congregation. I'm sure it would depend on if they want a relatively short term transitional pastor (10 years or so) or a "Young MacArthur" who will hopefully be there for a generation.
MacArthur is only the third pastor that church has had. The first two both died within a year or two, then MacArthur arrived in 1969.
As far as going covenantal, unless they get a word from Abraham, Moses and maybe even Jesus himself, (which would involve them abandoning cessationism!) that just isn't going to happen. For lack of a better term, they've got a whole "machine" there that goes the other direction. The Masters Seminary is probably the main one putting meat on the table from a dispensational standpoint these days. They've also got several dozen elders there that are all presumably in full agreement with their statement of faith. I'd be shocked if his successor isn't a graduate of The Masters Seminary. I've wondered if it won't be one of the young men who preaches there fairly regularly, but I could certainly be wrong. There have been assoc. pastors there in the past who have been very familiar to the congregation.
