Not really combining, but I'd like that Fallout 3's Enclave Armor would appear in NV, maybe even in a small role like a dead guy's clothes, but to show some hint that Enclave personnel tried to retreat back into West after they were toasted in the East Coast.
'Cause, hell, the Enclave is like the Master's army. No matter how many you kill, no matter how many HQ's you blow up you just can't destroy them all.