I'm assuming it'll be like what happened with FF16 a couple of days ago. Media gets to play around with it for a bit, interviews, and B-Roll footage shown in any uploaded videos.

Earlier this month, we featured four amazing community Forge creations in the Community Collection playlist, which has been the most popular Halo Infinite playlist since the game’s launch.

Forge:

Really showing how important Forge is to get right on Unreal Engine.

Yeah, I do not see it happening.  Working in Unreal for a little bit, it really doesn't seem designed for what Forge does.  If they accomplish the task its going to be severely scaled back unless Epic have been holding back some tools to make it a reality.

Reportedly Microsoft has a prototype of Halo Infinite's Forge Mode mapmaking tool running in Unreal already, although a prototype doesn't tell us how scaled back it is (if it is). Could see them working directly with Epic to implement it.

I'll say again, any engine swap which can't incorporate Forge at a level of scale it is currently at would be a major mistake and I think 343i know that which is why Forge is the first thing translated over to Unreal Engine so hopefully they know what they're doing with this switch.

I don't see any reason why it wouldn't be possible. 

Unreal is very customizable.

You say that, but only evidence I've ever seen points to the contrary lol. 

I'm sure it's entirely possible with the proper amount of work, but I still have yet to see the extent of customizability like Forge has in an Unreal game.