Every show has its peak and eventually sees its viewership numbers fall to the point where the network will pull the plug. That's really not a comment on this show's merit. TCoOI has had a phenomenal run. Traditional network shows (before the reality era) would dream of getting to 100 episodes and moving into syndication. TCoOI is already well past twice that. I believe its peak viewership season was three to four years ago, based on the promotional language at the time ("number one ..." blah blah blah "on cable"). One wonders why eight or nine seasons was not too much for those audiences but twelve is? My personal favorite season was when they had heavy duty excavations going simultaneously on multiple fronts including the big coffer dam on Smith's Cove as they worked on the U-shaped structure. Those works were visible on Google Maps with the satellite overlay at the time!
As someone else pointed out, this series may still be in the top five at History, which will probably ensure its run for at least another couple of seasons. At some point the principal "cast" will start to age out of wanting to be involved (in the production, not the hunt), but who knows, maybe Alex Lagina and Peter Fornetti, et al. can carry the franchise another decade or two? I'll keep watching.
Oh and BTW, actors in scripted shows would be in SAG/AFTRA or its Canadian equivalent ACTRA. The Curse cast are not members, therefore not actors. QED.
--GT