If your theories are true and it doesn't end up reopening post-corona, then that would make it the joint shortest-lived attraction in park history alongside the Space Boat, which was only in place during the 1983 season!
In all honesty, if the rumours of it being a temporary attraction are true, then I could see it being removed as well. I'd imagine it costs a lot to run, and it wouldn't be a very appropriate thing to operate while social distancing is still in place. Come to think of it, how on earth will Merlin's midways operate with social distancing in place, as I'd imagine that social distancing is complicated to impose in some of their midway attractions? I'm sure they'll find a way, though; they always do!
If they do end up removing the Dungeons, then I think it would be a fantastic expansion opportunity for The World of David Walliams; that ride system could make another nice family dark ride for the area, and they could even fit another ride in the area outside the building. I reckon a family flat ride of some form could fit where those water walkers are near the Burger Kitchen (or at least used to be. I'm not sure if they're still there now).