For the purposes of the demos, I believe ammunition capacity was made infinite, and will be adjusted (and can probably be upgraded) in the beta and release. On weapon durability, I doubt it. To me, such a mechanic seems a tad tiresome, and such effects will be amplified with the lower drop rate of guns in comparison to other games. About consumables, I'm not sure. Maybe health packs will be implemented, or health regenerating, the topic has not received much discussion.