This should be looked at in two ways... Game title specific and Elite (multi title) overall ranking.
What do I mean.. Well as it is now Elite events are only attached to MW3 hence our present clan rank is also attached to MW3.
When BO2 come out we will have a new set of events for our clans to earn XP. When this happens Elite should institute a multi game title leaderboard that will accommodate clans that play more than one title.
So MW3 clan ranking is what it is today. BO2 we start at 0 and have to earn Clan XP in BO2. Also a new ranking based on the sum of all titles for the Elite ranking.
ie
MW3 = Clan Level 50 (finnished)
BO2 = Clan Level 10 (in progress)
Elite = Clan Level 60 (always in progress)
If they do not implement something like this and instead add additional levels, at +10% XP needed per level, attaining levels on subsequent titles will get insanely difficult to get.
Gaining unlocks that are title specific is the main motivator for grinding thru clan events and with out clan ranking by title this will not be possible.
That's my 2 cents. I am for a new title everyone starts at the same level, BUT and overall ranking of multiple titles too.
ie
MW3 = Clan Level 50 (finnished)
BO2 = Clan Level 50 (finnished)
new title = 10 (in progress)
Elite = Clan Level 110 (always in progress)