This is the scenario that I prep for. Doing quite well in that area, btw.
While I agree the scenario is plausible- its in line with my "release a bio weapon" example, but its more problematic for TPTB. The Cities will indeed implode, but that means a loss of mostly- their useful idiots and supporters. Even in the cities I would expect more conservative types to be prepped and ready- though many may evacuate to rural areas. 3 days without water. 3 Weeks without food. The Cities will be ghost towns in the first 2 months. Maybe 3 months if cannibalism becomes widespread. Survivors will be battle hardened, armed and probably not to glad to see the "Saviors" show up - either because they are brutal criminals or because they are conservative liberty minded folk. IN the rural areas it will be basically nothing but conservatives left. Your target population for control is now 90% liberty minded - and will demand elections in short order.
In the "chaos" periods, many areas are going to fragment and form their own power structures, who may not lay down arms so Gracefully when TPTB arrive to "save us" - IN many cases the people- especially in rural areas, will not starve within 3-6 months. The threat from the cities of looting and gangs will force them to organize an effective militia force, and there are a lot more people "prepping" at the basic Beans, Bullets and Bullion level than there were four years ago. . Most amateurs I am in contact with who looked at me funny at first, are now armed, stocked with ammo and at least 3 months provisions and a supply of Clean water. The longer TPTB wait to arrive, the more prepared and less in need of help the rural areas will be. They can't really decapitate the liberty movement, without starting the full one war - there are too many to kill. The whole point of the plan is to have many independent cells. If word of executions gets around, TPTB won't be greeted as saviors.
And these " Saviors"- where are they coming from? Who is paying them? Just in the food store and ammo the Fed has stocked? With Chaos reigning outside the military bases and these men not being deployed- how many will desert to go home to protect their families? Any order to impose martial law on the American people will probably fragment the military. And order preventing them from being deployed immediately will probably deplete their ranks. Any overt aggression against liberty leaders would accelerate both effects.
A War in Syria or elsewhere would help with these problems, but alleviate them.
In short, I don't think economic collapse is enough of a disaster by itself to allow this to succeed. It happened in Argentina- they got by - and without being heavily armed. Its a different culture to be sure, but I don't think its enough to cause the sort of damage they would need to do to really stop a resistance. You would need an EMP pulse or the Bio -weapon something that really F's things up for resourceful individuals. - Less transportation, no power for pumps for sanitation or even local wells, water, oil, gas etc. No way to run the tractor. Far less knowledge on how to farm that way etc. the whole "One Second After" scenario.