Overview taking into consideration all Mechs/vees shown/mentioned/hinted at so far
(ACS Patreon, Mercs KS announcement, KerenskyCon, WolfNet Ep. 50, GenCon).
Items in italics have yet to be confirmed as being part of below mentioned packs.
Comments in italics are assumptions/personal opinion.
Mercenaries Box Set (GenCon)
1 - 2x Inner Sphere Standard Battle Armor (Ambusher, 6"j) - WolfNet Ep. 50 confirmed
2 - 2x Maxim (Size 2, Striker, 16"h)
3 - 2x Galleon (Size 1, Scout, 12"t)
4 - Firefly (Size 1, Striker, 10"/8"j)
5 - Starslayer (Size 2, Skirmisher, 10"j)
6 - Caesar (Size 3, Brawler, 8")
7 - Devastator (Size 4, Juggernaut, 6")
8 - Flea (Size 1, Striker, 16")
9 - Chameleon (Size 2, Scout, 12"j)
10 - Quickdraw (Size 3, Skirmisher, 10"j)
11 - Ostsol (Size 3, Skirmisher, 10")
IMHO, it is feasible that IS Standard BA could (also) get a standalone ForcePack
or maybe even a Battlefield Support-style release (2x Maxim, 2x Galleon, 4x BA).
Taking a cue from the Retaliation Pack from the Clan Invasion KS, we might also
see the Mechs from the Box Set as a standalone pack (or possibly a pair of Lances).
Clan Direct Fire Star (GenCon)
12 - Grizzly (Size 3, Skirmisher, 8"j)
13 - Rifleman IIC (Size 3, Sniper, 6"j)
14 - Highlander IIC (Size 4, Missile Boat, 6"j)
15 - Bane (Size 4, Sniper, 6")
16 - Phoenix Hawk IIC (Size 4, Sniper, 10"j)
Clan Cavalry Star (GenCon)
17 - Locust IIC (Size 1, Striker, 16")
18 - Jenner IIC (Size 1, Striker, 18"/14"j)
19 - Griffin IIC (Size 2, Missile Boat, 12"j)
20 - Shadowhawk IIC (Size 2, Striker, 12"j)
21 - Black Python (Size 3, Skirmisher, 10"j)
Battlefield Support : Recon & Hunter (GenCon)
22 - 2x Warrior VTOL (Size 1,Scout, 18"v)
23 - 2x Skulker (Size 1, Scout, 14"w)
24 - 2x Ontos (Size 4, Juggernaut, 6"t)
25 - 2x Behemoth (Size 4, Juggernaut, 4"t)
Battlefield Support : Assault & Cavalry (GenCon)
26 - 2x Pegasus (Size 1, Striker, 16"h)
27 - 2x Condor (Size 2, Striker, 16"h)
28 - 2x Schrek (Size 4, Sniper, 6"t)
29 - 2x Demolisher (Size 4, Juggernaut, 6"t)
Battlefield Support : Objectives (GenCon)
30 - Mobile HQ (Size 1, None, 12"w)
31 - 2x Mobile Long Tom (Size 2, Missile Boat, 4"t) & trailer - WolfNet Ep. 50 confirmed
32 - 2x MASH (Size 1, None, 10"w) - WolfNet Ep. 50 confirmed
Battlefield Support 4 (conjecture)
33 - 2x Vedette (Size 2, Brawler, 10"t)
34 - 2x Manticore (Size 3, Brawler, 8"t)
35 - 2x SRM Carrier (Size 3, Ambusher, 6"t) - KS announcement confirmed
36 - 2x LRM Carrier (Size 3, Missile Boat, 6"t) - KS announcement confirmed
Inner Sphere Recon Lance (GenCon)
37 - Javelin (Size 1, Striker, 12"j)
38 - Spector (Size 1, Striker, 14"j)
39 - Firestarter (Size 1, Scout, 12"j)
40 - Ostscout (Size 1, Scout, 16"j)
Inner Sphere Pursuit Lance (GenCon)
41 - Dervish (Size 2, Missile Boat, 10"j)
42 - Clint (Size 2, Striker, 12"j)
43 - Hermes II (Size 2, Scout, 12")
44 - Cicada (Size 2, Scout, 16")
Inner Sphere Security Lance (GenCon)
45 - Scorpion (Size 2, Skirmisher, 12")
46 - JagerMech (Size 3, Sniper, 8")
47 - Whitworth (Size 2, Missile Boat, 8"j)
48 -
Also requires a Scout, so either Charger or Vulcan.
Inner Sphere Assault Lance (GenCon)
49 - Goliath (Size 4, Sniper, 8")
50 - Hoplite (Size 2, Sniper, 8")
51 -
52 -
Shogun probably goes here.
Inner Sphere Heavy Recon Lance (GenCon)
53 - Assassin (Size 2, Scout, 14"j)
54 - Ostroc (Size 3, Skirmisher, 10")
55 -
56 -
Still requires a 2nd Scout, so either Vulcan or Charger.
Currently unallocated Mechs
Shogun (Size 4, Missile Boat, 6"j)
Vulcan (Size 2, Scout, 12"j)
Charger (Size 4, Scout, 10")
Merlin (Size 3, Brawler, 8"j) - Patreon hint
Logical assumption : one more Mech to fill out the aforementioned ForcePacks.
My money is on the Mauler, which would tick all the boxes for the Assault Lance.