Thats about the only difference the game will be able to make between different infantry regiments at this sort of scale. But, surely we wont be seeing units like the Royal Marines and the Para`s in the campaign because the game seems to deal with a single Brigade or Battle Group unit. As far as I know, Marines and Para`s wouldnt be operating in the armoured infantry role with attached armour callsigns. I`m setting my hopes on a campaign centred around a Household Division Battle Group. Light armour from the Blues&Royals, Chally`s from the Lifeguards and Warriors and dismounts from the Guards.
But at the end of the day, the only difference will be in the campaign briefing, which you can probably edit anyway.