Adding 5 would be redundant. Adding Reach and ODST Firefight would be able to fulfill one of 343's secondary goals with MCC, to bring all of the previous gen Halo titles to one modern console in their entirety, but 5 already exists on a modern console, is up to par in every aspect of a standalone game on that console, already runs at 1080p 60fps, and is already 100 gigs alone.I don't agree with you, point being if you don't want to install halo 5 you don't have to - saves you however much GB, to have the option would be nice. Me personally I would Install everything, reach already has a dedicated loyal fan base that I don't see playing any other halo game so it will not split the community at all - if anything it will raise the population as the people playing reach now will obviously move to MCC to play it if it's updated to 60fps at minimum. I would play reach, halo 3, halo 2 and halo 5, and warzone. As much as people don't claim to not like 5 - there are a lot of people (myself included) that do like 5 and so adding these games to MCC will bring these guys over who may end up actually trying out other games while they are on MCC from time to time and vice versa (raising the population) , and I suppose it won't actually be hard to connect with the halo 5 servers as they are on dedicated servers anyway so halo 5 MCC and halo 5 players will be able to play crossplay (no community loss). This idea is perfect for the digital future - meaning the game will get ongoing support for years to come (all bugs ironed out) and future things can be added - when we move to next gen gensoles this game can carry on instead of starting the ports all over again and then even the gen after that if thats still consoles or streaming it just makes sense to carry on supporting the work you have already done instead keep starting again. if you ever want to play halo you just boot up the hub and pick your game, all halo players in one place. simple! if you don't enjoy or don't want that game - just don't install - it doesn't affect you because you have the option. whether that's because you don't like the game or wanna save the GB...
Adding on to everything I just stated, including another game would split the population even more. Multiplayer would now become a 7 way split, with CE, 2, 2A, 3, Reach, 4, and 5 all having their own playlists. Quite honestly, I don't even fully support adding in Reach anymore because that would even be too much of a split. The game would be completely divided between casual players splitting into Reach, 4, or 2A, and competitive players splitting into CE, 2, or 3. A remaster in the spirit of CEA or 2A would be perfectly fine.
MCC was only meant to include the Master Chief Saga up to 2014, a year prior to Halo 5's release. Couple that with the fact that it is completely functional on the Xbox One in 1080p 60fps as a standalone game (minus some bugs and glitches people complain about), there is no way to justify adding Halo 5 to the Master Chief Collection. Just buy Halo 5 and be done with it. All it takes is quitting out of MCC and starting up 5 from your dashboard.
You may not have to install Halo 5 with Intelligent Delivery, but adding in 2 more games to the list will divide the playlists even more, which in turn will divide the community even more, regardless of who installs it and who doesn't. More people will flock to one game/playlist, and more playlists will become desolate wastelands with no one in them at any given moment in the day, a la Team Objective. This will make it inevitably harder for players to play what they want, unless all they want to play in MCC is Halo 3 Social 4v4 and BTB, which are the most popular modes in MCC (all you have to do is walk into the cross game Slayer or BTB playlists to see that).
Have you also considered that 343 doesn't want 100 playlists in MCC? That's why they're significantly limiting the number of playlists in each game. Many playlists would get cut from the ported version of Halo 5, which really makes no sense when you can just buy the game and have all the playlists MCC wouldn't.
MCC including Halo 3 and 4 basically killed the standard versions of the game. 3 is obviously deserted, and 4's population is slowly shrinking. Adding in 5 will either leave standard 5 empty, or MCC 5 empty. Your idea of dedicated servers is wrong. Both games may run on dedicated servers, but that doesn't mean all dedicated servers are compatible with one another. MCC will run on dedicated MCC servers, and Halo 5 runs on dedicated Halo 5 servers, and crossing the two won't work, just like how cross-platforming Halo 3 is impossible. Both servers run on different infrastructure. Even if the servers could somehow be merged, this would cause a lot more traffic jams, and game crashing, loss of connection, and so on will become amplified.
Let me just add this: people that own standard Halo 5 will notice a significant player drop if it were added to MCC. A fair amount of players would flock to MCC for no real reason, other than the fact that it saves them a whole 30 seconds over going from MCC to Halo 5, when really nothing gameplay wise would be effected. Obviously, if Reach were ported, Reach would be the new Halo 3 in terms of population, because people would much rather play Reach in 1080p 60fps with all of the other Halo games right next to them than 720p 30fps and have to transition to a whole new console if they wanted to play MCC.
Like I said before, not only is 343 not looking to merge any more games, and are only looking to deal with what they already have, but Halo 5 already runs at 1080p 60fps, already keeps up with current games graphic wise, and already has its own problems that need to be fixed that will only grow in scale if it's merged with MCC. I don't understand how you think MCC doesn't have enough already. Stock, it's 30 dollars new for 4 campaigns, 5 games worth of multiplayer, 3 Forge variants, and Custom Game lobbies for every title, all running at 1080p 60fps with a completely remastered Halo 2, as well as the remastered CE, with the ability to play CE through Live for the first time ever, and the ability to play Classic Halo 2 through Live since 2010. That's a lot of stuff, and considering Halo 5 hasn't had the best time in the markets, Halo 5 is only 20 bucks from the MS Store right now (can be found cheaper from used retailers), with it being a standalone game that already has a campaign, multiplayer, custom games, forge, and so on. Games like Black Ops II and GTA V are not only older, but have less to do, and still cost 50-60 bucks, the price that they had at retail when they were released 6 and 5 years ago, respectively.
Would you rather have an entire list of cons for adding Halo 5 to MCC, with the only pro being that you get to save a whole 30 seconds worth of boot up time, or would you rather just shell out 20 bucks and have a much better functioning Halo 5, as well as a much better functioning MCC, implying you already own it?