"The First Five Books (after core)" seems to demand that we know what "Core" is.
I'd like to see this:
"Core"
1) Starter/"D&D Adventurer's" box set. Details starting play and levels 1-5. Players Guide, DM's Guide, Monster Digest (50 creatures to get started with), Magic/Spell Digest (all caster classes spells but only a limtied list of what they need for PC levels - not "spell levels"- 1-5), Self-contained Adventure (a la village of Hommlet more than Keep on the Borderlands: with 3-6 possible adventures: at least , an NPC/interaction based adventure, Skill-based adventure/exploration, Heavy combat-oriented adventure and a "classic" dungeon delve that should incorporate all of these things), set of dice.
2) "Advanced Player's Handbook" detail levels 1-20. Expanded Skills, maybe the full list of Races and Classes if these aren't all presented in the Starter Box.
3) "The Dungeonmaster's Guide." With everything that a DMG needs to
have for the "full" (levels 1-20) game.
4) "The Monster Manual." Significantly more extensive and thorough than the Monster Digest of the Adventurer's set. Brilliantly illustrated.
5) since we know that Forgotten Realms is the default setting for 5e, then a "Forgotten Realms Campaign Setting" book. This should be put out as part of the core for those who want to jump right in.
There's our core. All need to be published at the same time...or within a span of a month or two to get all 5.
And a month after that...
-1a)
"The Adventurers' Path" Series. 4 or 6 fulling fleshed out adventure modules of all kinds and foci for levels 1-5.
Following that...(what the OP is actually asking for in this thread)
6) The Expert/"Champions" box set. Detailing levels 5-10. Players Guide, DM's Guide, Spell Digest (not adding to the low level spells of the beginner set, just introducing spells needed for PCs levels up to 10.) A Monster Digest is not necessary here since you would already have the original and the full MM (which I expect to have, roughly 200 "monsters" in it). But, if necessary, another minimal 50-creature Monster Digest.
7) "The Legends Handbook." Details for players and DMs on "Epic" style game play (levels 20+)
8) "Deities & Demigods." Detailing a
few pantheons (a "core" Greyhawk, maybe a pruned down "core" of FR, 1 or 2 real world pantheons, but really barebones of those). But more importantly guidelines for creating your own! Guidelines for creating/incorporating various religious organizations, temple/church hierarchies, cults. World mythologies that make sense and can be applied to any setting you want. Setting up a mono-/duo-/and polytheistic mythology, an animist/spirit-based (as opposed to "god based") system.
9) "The Dungeonmaster's World Builder." Detailing creating and expanding your own settings...and everything that goes into that: making various nations/governments, economies, natural (and supernatural) resources, "believable" settlements/communities, NPC creation, Domain/kingdom creation, Mass Combat, etc. etc.
10) "Manual of the Planes." Details a "default" cosmology and gives ideas/guidelines for generating your own. Introduce "Plancescape" type adventuring, Sigil, etc. Preferably packaged with a Plane-jumping/traveling adventure.
Also, dispersed out through this time:
-6a)
"The Champions' Quest" Series. 4 or 6 fulling fleshed out adventure modules of all kinds and foci for levels 5-10.
-11a) [see below]
"The Heroes' Challenge" Series. 4 to 6 fully fleshed out adventure modules of all kinds and foci for levels 10-20 (say, 2 or 3 for 10-15 and 2 or 3 for 15-20).
-7a)
"The Legends' Myth" Series. 3 fully fleshed out adventure modules of all kinds and foci for levels 20+....for those that pick up the Legends Handbook and want to dive straight into Epic play.
Again, all of these "secondary" books and products need to be released around/within the same timeframe, say within 3 to 6 months.
[PS: This is also the timeframe when the NEW 5e-modeled D&D cartoon should begin airing.
]
Moving on...to the "not asked for" third set of releases...
11) The "Heroes" Box Set: Players guide, DMs Guide, Spell Digest. Detailing play for character levels 10-20. (DMs are pointed to the "new Fiend Folio" for additional monsters and creatures appropriate for this "higher level" play)
12) "The Fiend Folio." A Monster Manual 2 but chock full of things we've NEVER seen before (and/or stuff people are screaming for that were cut/forgotten in the original MM). Or maybe with a focus on extra-planar creatures?
13) "The Greyhawk Campaign Setting." Fully fleshed out, like the FR book, for the original Greyhawk setting...preferably with a COMPLETE version of Castle Greyhawk packaged with it.
14) "The Explorers Survival Guide." Basically a "Wilderness Survival guide" and "Dungeoneer's Survival guide" rolled into one. LOOOOTS of different add-on modular stuff: extra/expanded Skills, detailing types of terrain and threats thereof, exposure/fatigue/movement rates, sea-bassed and aerial adventuring, maybe an extra/new class or variants or two. (My reasoning for this here/this late in the release schedule is that, basically, players and DMs should have a complete mastery and explored many different options and modules of play with the "basics" stuff before adding MORE modular options they might want to incorporate.)
15) "The Planescape Campaign Setting". Fully fleshed out, a la FR and Greyhawk, expanding on what was introduced in the Manual of the Planes and presenting the full blown "Planescape" setting as its own world(s) for use.
I thiiiiink...that about does it for me. The rest can be various supplements and adventure modules geared toward different levels of play (within the existing "Series" presented above) and/or Campaign Setting specific things:
"Adventures in...[FR, Greyhawk, Planescape, Ravenloft, etc.]" Series; "Races of the Planes"; "The Complete Elves of the Realms" (for FR, obviously); "The Greats of Greyhawk" (NPC compendium and possible adventure ideas in GH); etc. etc. ad infinitum.
AND, I want to be clear in noting, as much as I LOVE the classic modules and stuff, all of the published adventures (either as complete campaign paths or individual contained stories) should be NEW...ok, maybe ONE homage to a classic in each series reworked for 5e...but all of the others should be NEW!
We've "Returned" to the ToH and the KotB and the ToEE and all of that. If they want to release a "5e converted version of whatever", that's fine. But no more "rewrites/additions" just convert the old modules and leave it at that. We don't need to "Return to..." anywhere anymore. NEWLY WRITTEN adventure modules, please.
--SD