At the three-minute mark of the season 2 trailer of the MacArthur Centre Podcast - The Expositor...
"Finally, we will answer the question everyone is asking. Who is it who will take over for John MacArthur when he's gone? What's the succession plan? Who is the next JMac?"
There's eight episodes planned for season 2 so guess this will be answered in the last episode of the season.
The Expositor | The MacArthur Center Podcast
Till then check out his resources in Logos: Search Results | Logos Bible Software