Oh man I really hope that's not the case - I hate microtransactions. But in the warzone b-roll footage (@ 2:25) the player is shown using the system, and you use "energy" as currency to get the power weapons. Right after the next guy spawns with the sniper, you can see him earn energy in the bottom-center of his HUD (watch it go up when he headshots a guy).

So from what I saw it looks more like currency earned in mission (as opposed to in game). Kind of like counter strike, how you get dollars and can buy guns in the next round.

Actually I'd say that the "energy" is identical to the ordnance points you earn in halo4's infinity gamemodes, except now the way you spend it is different.