I believe the Kennedy version was the first to offer casting as in the closing credits, it states "Contestants were interviewed in advance and must meet eligibility requirements". Oddly though, the Davidson credits are back to the daytime's "Prize winners must meet eligibility requirements", though it would seem like that version would be more inclined for casting. We'll probably have the 50th anniversary special taped after the regular season wraps production from the way it looks right now, with perhaps S50 itself as a buildup to it. I wouldn't mind a series of specials next summer on a night that ABC doesn't have any fun & games since the 1986 specials were used to promote 15 years on CBS, and with it, a freshened set for a return to normalcy.
If they do go on with casting, they should have "mock game" segments to ensure that contestants know how to play or be energetic. Aren't there special interview segments where "The new Stan" will chat with the players, and then select who will get to go on? I'd imagine those who aren't selected could still get audience tickets which is how limited audiences could work, with so far, no OCA yet.