Delta's Other (Half-Hearted) Bag Fee

I recently was reading through the Carry-on Baggage rules on delta.com and came across some verbiage I don't recall seeing before:

When oversized bags do not fit in the overhead bins, delays occur. Fees will be applied to the oversized bag if it has to be checked at the gate.

I, like most travelers, understand the delays that are caused by other passengers bringing oversized rollerboards as carry-ons, just to find that they do not fit in the overhead bins.  You end up with a line all the way up the jet bridge and the offending passenger fighting the flow of others boarding, attempting to get their bag back to the front of the plane to be gate checked.

There is no doubt that the advent of checked bag fees has certainly not helped the situation.  The airlines (except our token holdout, Southwest) have created this monster.  By charging passengers a fee (relatively nominal for most passengers only checking 1) to handle their baggage for them, they have created a financial incentive for people to stuff as much as possible into their carry-on.  This crowds airport terminals (especially older/smaller ones), slows the boarding process in general, and gives consistent fodder for discussions about how people dislike air travel.  And we don't want to forget the opportunity created for Southwest to market their contrary policy.

What is striking to me about this statement on Delta's website is the general lack of specifics.  While the context on the website around this statement goes on to explain the limit to the size of a carry-on (45 inch max of length, width and height combined) and the fact that carryone baggage must fit "easily" within the airline's "Carry-on Baggage Check" stations located in the terminals.  There are some questions, however, Delta has left unanswered:

1. How much is the fee?  Seems extremely odd that the size of the fee is not stated.
2. How is this intended to be applied to passengers on Delta's substantial fleet of mainline aircraft with "under-developed" overhead bin space? 
3. Does this policy also apply to passengers traveling on a Delta Connection regional jets? (only a few have any reasonable overhead bin space)
4. How do they intend to collect such a fee during the boarding process?
5. Would this fee apply to Medallions who already don't pay checked bag fees?

Each aircraft model is a little different, and any remodeled interiors (seem pretty rare on Delta equipment) might change the overhead bin space. (The Boeing Sky Interior looks pretty cool, btw) But the fact remains that it's hard to truly predict the overhead bin space that will be available on a particular flight.  Mix that with what "zone" you might be assigned, and it's entirely possible that the plane with a relatively large availability of overhead bins could be completely full by the time someone in Zone 4 gets there.  Will these people be charged this fee?

I recently boarded a flight from ATL to SDF at the very end of the boarding process (just about missed the connection, because of a delay on my first leg).  I had my normal carryon rollerboard with me (not "oversized" by Delta's deifintion, btw), and volunteered to go ahead and gate check my bag, expecting the overhead bins would be completely full.  Instead of being given a pink tag (as I expected), I was given a white one, with a carbon copy.  Found out later that my bag was checked through to baggage claim instead of returned plane side.  A related coincidence?

My biggest questions are around how Delta would operationalize such a fee?  How, during an already pretty challenging boarding process would a gate agent, or a a flight attendant be able to process payment for a fee?  Credit?  Cash? (delta mainline onboard purchases are already credit card only) Will these paid-for checked carry-ons be passed through to baggage claim, or returned plane side?

Realistically, it seems Delta is just covering their bases here, and not doing it very convincingly.  If they intended to collect these fees, we would know the cost.  There would also be much more detail around when it would apply.  My guess is that this statement is a (first) step in trying to deal with the natural passenger reaction to checked bag fees.  It seems Delta agents or attendants could today trot out this "policy" when dealing with unruly passengers throwing a tantrum about having to check their obviously oversized carryon.  They can refer to this policy and threaten to charge them a fee on top of forcing them to check their bag. 

In the end, I think it's a generally empty threat.  Even we I asked @DeltaAssist on twitter about this reference, here is how the exchange went:

Didn't really answer my question about price, and my guess is that this is by design.  Delta doesn't intend to charge the fee at this point in time.  But, it could be a sign of things to come.