I was reading through the thread catching up on what everyone else was saying, but I do have something on the topic. Some other people've said that MS (at least for their own 1P games) seems to be treating GamePass as a
pseudo-F2P model, where they basically have the "base" game in GamePass but the additional DLC being stuff you have to buy separately. That sounds like an accurate read on the way they're going about the model, but if that's how MS views it, they have some big problems.
First is that actual F2P games are
fully F2P. If MS wants to treat GamePass as a pseudo-F2P model, they have to answer why they're charging $10/mo - $15/mo on accessing the games, if they then plan to not include DLC which has to be purchased separately. You don't have to pay for F2P games to play multiplayer online, even on Xbox, so what is the $10/mo getting you? A catalog of 3P games? Okay, but what if those 3P games only include the base versions and no extra DLC as well?
Also if you look at it from that POV, it'd be MS shifting somewhat on what the main hook for GamePass was meant to be. From having all 1P games Day 1, to cheaply having access to a lot of 3P games (most of them legacy, outside of some of the indies). Some could say they're still keeping that marketing hook , "all 1P games Day 1", except we've already seen that isn't necessarily true, either. Forza Horizon 5 was available for early purchase ahead of going into GamePass. It was by a few days, but what if MS does that with future 1P games and extends the window between the game up for purchase and then going into GamePass? That could be another means of them to monetize their content outside of GamePass.
One other thing, I think them making the FH5 DLC something outside of GamePass has some massive implications for some stuff even I thought they would do once they got ABK. Everyone thinking the COD games will be in GamePass Day 1 need to drop that idea immediately; there is simply too much money to be made through upfront sales for MS to jeopardize cutting into ANY of that by having those games in GamePass Day 1 or within the year of their release. Now, I
thought they would work around that by including DLC content in with GamePass subs, but there's too much money in that, too, so that isn't going to happen, either, especially considering the FH5 DLC skipping GamePass.
I guess the one thing they could do, is make it so where COD DLC and MTX items come with a discount if you have an active GamePass sub. That way, they can still encourage new GamePass subs (and convince current ones to stay), without cutting into sales revenue for the game, DLC, or MTX. Maybe you get a 15% discount on all purchasable DLC/MTX items and Season passes for COD if you have a GamePass subscription. I can definitely see MS doing that. However, them actually putting that DLC/MTX in for free as perks of a GamePass sub? Not happening whatsoever, what they're doing with the Hot Wheels FH5 DLC is enough to convince me of that.