
Add HOLDS to airports that require them and realistic reasons for doing so.

Also make it so that traffic contributes to the probability of holding

That would come under “realistic reasons for doing so”

It’s funny because in real life you would not like to be stuck in a hold. So while I would say this should be a tool available to BATC for traffic spacing and other issues, I hope ingenious vectoring comes first. Anything is preferable over just making inconvenient AI traffic disappear however.
I will back @talentless here, hopefully great vectors will take priority over HOLDs. But the ability to ask BATC for a HOLD would be a great addition. Not only in the case of a simulated emergency, but in general. No pilot wants to HOLD, but we can train that in the sim. More options, more better.

I hope “all” possibilities come to fruition and a glance at the road map suggests they will.
Holds are used in case bad weather also, like in this moment in Milan, with 4 planes waiting out of LIML. It’s not only traffic the reason.
Useful for bad weather, maybe BATC uses the metar and makes a decision on whether the visibility is good enough to land

I suppose with the implementation of traffic in BATC, holds are becoming essential.
Adding Holds would be a great feature in Sim Navigation
It would be great to let AI hold too. BATC does pretty well funnel planes into arrival, but sometimes 4 planes are too compressed together coming into the airport, and sometimes a A380 can fly as slow as 70 knts to create spacing.
I had 2 landings turn to “go around” in a row I believe because the cross winds were excessive. While a hold may not have fixed that if the winds were not going to die down, it would have been preferable to an aborted landing.