All info taken from Total War Warhammer forums:
https://forums.totalwar.com/discussion/179907/the-data-mined-dlc-faction-list-analysed/p1
What can it tell us? It can tell us what factions CA planned to add and in roughly what order at some point prior to the game's official launch. Given CA's statements that the list is out of date and that their plans have expanded, my guess is that we will be getting more than what we have listed, so the numbering may end up being off. For example, we may get two DLCs between the Beastmen and Wood Elves, but in all likelihood the rough order will probably be pretty close. We may get more Campaign packs as well, but there's no way to know that beyond the information we have for Beastmen and Wood Elves. So...
*****!!POTENTIAL SPOILERS!!*****
PART I - The pre-existing factions:
You'll notice suffixes at the end of some faction names. "_qb#" indicates a copy of a faction used in Quest Battles, not necessarily a faction with quest battles. Factions that have at least one "_qb#" are not necessarily going to be playable, but it's a pretty good indicator that factions lacking quest battle copies were not planned to be made playable at the time the list was made. The "_rebels", "_separatists", and "_waaagh" suffixes are self-explanatory.
Also note that there are no "DLC##" prefixes for either Chaos or Bretonnia. This is because those factions are already on the map and coded into the game, even though Chaos was the first DLC and Bretonnia will be made playable later.
wh_main_brt_artois
wh_main_brt_bastonne
wh_main_brt_bordeleaux
wh_main_brt_bretonnia_qb1
wh_main_brt_bretonnia_qb3
wh_main_brt_bretonnia_qb2
wh_main_brt_bretonnia_rebels
wh_main_brt_bretonnia_separatists
wh_main_brt_carcassonne
wh_main_brt_lyonesse
wh_main_brt_parravon
wh_main_chs_chaos
wh_main_chs_chaos_qb1
wh_main_chs_chaos_qb2
wh_main_chs_chaos_qb3
wh_main_chs_chaos_rebels
wh_main_chs_chaos_separatists
wh_main_chs_chaos_separatists_sorcerer_lord
wh_main_dwf_barak_varr
wh_main_dwf_dwarfs
wh_main_dwf_dwarf_ai_separatists
wh_main_dwf_dwarfs_qb1
wh_main_dwf_dwarfs_qb2
wh_main_dwf_dwarfs_qb3
wh_main_dwf_dwarf_rebels
wh_main_dwf_dwarf_separatists
wh_main_dwf_karak_azul
wh_main_dwf_karak_hirn
wh_main_dwf_karak_izor
wh_main_dwf_karak_kadrin
wh_main_dwf_karak_norn
wh_main_dwf_karak_ziflin
wh_main_dwf_kraka_drak
wh_main_dwf_zhufbar
wh_main_emp_averland
wh_main_emp_empire
wh_main_emp_empire_ai_separatists
wh_main_emp_empire_qb_intro
wh_main_emp_empire_qb1
wh_main_emp_empire_qb2
wh_main_emp_empire_qb3
wh_main_emp_empire_rebels
wh_main_emp_empire_rebels_qb1
wh_main_emp_empire_separatists
wh_main_emp_hochland
wh_main_emp_marienburg
wh_main_emp_marienburg_rebels
wh_main_emp_middenland
wh_main_emp_nordland
wh_main_emp_ostermark
wh_main_emp_stirland
wh_main_emp_talabecland
wh_main_emp_wissenland
wh_main_grn_black_venom
wh_main_grn_black_venom_waaagh
wh_main_grn_bloody_spearz
wh_main_grn_bloody_spearz_waaagh
wh_main_grn_broken_nose
wh_main_grn_broken_nose_waaagh
wh_main_grn_crooked_moon
wh_main_grn_crooked_moon_waaagh
wh_main_grn_greenskin_ai_separatists
wh_main_grn_greenskin_ai_separatists_goblin_shaman
wh_main_grn_greenskin_ai_separatists_waaagh
wh_main_grn_greenskins
wh_main_grn_greenskins_waaagh
wh_main_grn_greenskins_rebels
wh_main_grn_greenskins_rebels_waaagh
wh_main_grn_greenskin_separatists
wh_main_grn_greenskin_separatists_goblin_shaman
wh_main_grn_greenskin_separatists_waaagh
wh_main_grn_greenskins_qb1
wh_main_grn_greenskins_qb2
wh_main_grn_greenskins_qb3
wh_main_grn_greenskins_qb4
wh_main_grn_necksnappers
wh_main_grn_necksnappers_waaagh
wh_main_grn_orcs_of_the_bloody_hand
wh_main_grn_orcs_of_the_bloody_hand_waaagh
wh_main_grn_red_eye
wh_main_grn_red_eye_waaagh
wh_main_grn_red_fangs
wh_main_grn_red_fangs_waaagh
wh_main_grn_scabby_eye
wh_main_grn_scabby_eye_waaagh
wh_main_grn_skull-takerz
wh_main_grn_skull-takerz_waaagh
wh_main_grn_skullsmasherz
wh_main_grn_skullsmasherz_waaagh
wh_main_grn_teef_snatchaz
wh_main_grn_teef_snatchaz_waaagh
wh_main_grn_top_knotz
wh_main_grn_top_knotz_waaagh
wh_main_ksl_kislev
wh_main_ksl_kislev_rebels
wh_main_ksl_kislev_separatists
wh_main_nor_aesling
wh_main_nor_baersonling
wh_main_nor_bjornling
wh_main_nor_graeling
wh_main_nor_norsca_qb1
wh_main_nor_norsca_qb2
wh_main_nor_norsca_qb3
wh_main_nor_norsca_rebels
wh_main_nor_norsca_separatists
wh_main_nor_norsca_separatists_sorcerer_lord
wh_main_nor_sarl
wh_main_nor_skaeling
wh_main_nor_varg
wh_main_teb_border_princes
wh_main_teb_border_princes_rebels
wh_main_teb_border_princes_separatists
wh_main_teb_estalia
wh_main_teb_estalia_rebels
wh_main_teb_estalia_separatists
wh_main_teb_tilea
wh_main_teb_tilea_rebels
wh_main_teb_tilea_separatists
wh_main_vmp_mousillon
wh_main_vmp_rival_sylvanian_vamps
wh_main_vmp_schwartzhafenrebels
wh_main_vmp_waldenhof
wh_main_vmp_vampire_ai_separatists
wh_main_vmp_vampire_ai_separatists_master_necromancer
wh_main_vmp_vampire_counts
wh_main_vmp_vampire_counts_qb1
wh_main_vmp_vampire_counts_qb2
wh_main_vmp_vampire_counts_qb3
wh_main_vmp_vampire_rebels
wh_main_vmp_vampire_separatists
wh_main_vmp_vampire_separatists_master_necromancer