I guess it depends partly on the monetization they'll use. Yes, games like Fortnite and Apex Legends are high quality games, but they can be free with no issue on the business end because they make so much with their MTX strategies in the form of crazy over priced cosmetics battle passes where you have to pay a subscription type fee to even be able to unlock exclusive skins.
Another factor is content. You mention Fortnite being free but it's not really comparable in my opinion. Besides cancer MTX systems, you've got to think about what is actually in the full package. Fortnite is multiplayer only with 3 modes (solo, duo, squad) with some event style modes coming and going (this is how it was the last time I checked). It also has 1 map. A map that changes per season, sure, but nonetheless just 1 map. Those two points and then untested weapons/things get added that get removed anyway. There's really not that much going on when you think about it, kind of crazy they had to cancel their other games like Unreal Tournament just to have 700 people work on broken stuff. Anyway, enough digging on Fortnite. Halo is not one sided. It's got SP and MP, with the multiplayer consisting of many maps and many modes. SP also years to make, with a lot of money going into artists and designers.
You say videogames cost too much these days but I actually think it's the opposite. Big AAA videogames cost tens of millions more than they used to, really they should be way more expensive. But the industry knows we already have a hard time justifying paying $60 for a new game, it's a risk. There's no way they could increase it and expect to sell so they bombard with MTX to make up for it and profit. They spent like 500 million or some stupid amount of money on Destiny 2 and then people are furious when an expansion is $40 lol. Not saying it's okay but hey there it is.
If 343i decided to make a Halo BR then yes I would say make it free because that's what it takes to go big in the genre evidently, I'd put up with the cancer battlepass system or whatever they'd try implementing. But Halo as a whole? I think it should be full price.
In a perfect world I'd say make the whole thing free to get as many people playing as possible but you'd know there'd be sacrifices made, and I'd rather have a solid full priced game with reasonable MTX than a free, content lacking game with horrible MTX practices.
EDIT: Sorry about the wall of text lol Very passionate about this topic.