My own wishes are largely just more kit, as is most of this thread.
The Australians, or at least the SASR.
MACV/US/ARVN arms:
M1A1 Thompson - This one should also show up in VC hands as they seemed to like the arm enough to copy it.
M-1D Garand - Actually, more Garand types would be preferred, but if I had to pick one? The M-1D.
Stoner M-63 LMG - No brainer.
M203 - It entered service in '69.
M1918 BAR
PAVN/VC:
Vz.58 - Apparently, US Army units taking part in LRRP operations had access to these, as well.
Uk vz.59 LMG
Ground vehicles, my interest largely lies in aviation so I can't get too specific on variants:
US/MACV/ARVN
M48 Patton
M113
M706 Commando
M551 Sheridan
PAVN/VC
UAZ-469
T-54/55
T-34
Aircraft:
USAF/USN/VNAF
O-2A Skymaster would be my personal priority given its significance to the subject matter, maybe O-2B for some PsyOps fun. I'm biased here since I've got stick time in the regular 337.
A Skyraider would be excellent, too. An A-1E or A-1H.
T-28C for the VNAF.
A-37 Dragonfly, because it never gets any love.
VPAF:
An-2, it's a pretty important flier for the Eastern Bloc, over all.
MiG-21, I don't really like to recommend fast-jets since I feel ArmA's strength lies in CAS or CAS adjacent kinds of platforms, but I'm sure many would like the aircraft often dubbed the 'Phantom's Foe'. It should also be noted the VPAF didn't have too many of these and they were very precious airframes. Of course, I'm biased when I say it's precious, of course! Either way, I can confirm 3 variants of MiG-21 used by the VPAF during the US involvement and they are the MiG-21F-13, MiG-21PF, and MiG-21PFM. I can't confirm the MiG-21MF and can outright discount the MiG-21bis as they didn't receive their first bis until '77. I'd love to provide information as best I can as I own books on the MiG-21. Specifically, Yefim Gordon's tome that has a registry of them.
Finally, terrains. So, this would be the most work intensive one given the insane attention to detail we have in Cam Lao Nam.
I'd like to see portions of the theatre represented in a 1:1 scale. Places with specific notoriety in the history of the conflict, like Ia Drang Valley, Hue City, and regions within Laos and Cambodia.
Either way, eagerly looking forward to what may come.