I see. Thank you. I am very relieved to find I actually understood that. 
So, what happens now? More bank failures? Gawd! It just never.stops.
Heh. I guess I missed one stimulus impact...institutional investors already holding long bonds...the Fed just propped up support for existing holders...so some pensions may benefit...as would any other holders...but what if any real stimulus will that provide? Retired folks aren't exactly a bunch of free-spending types ya know?! You want stimulus you hit the pre-retirement income groups, especially the 30-60 range where people are in their peak earning years.
Any banks on the edge could result in the failure rate increasing down the road, it is practically guaranteed if Fed solvency keeps getting eroded by the Neo-Keynesians and structural reforms and entitlement reforms remain elusive. The weak economy basically takes any consumer driven demand off the table and growth prospects dismal. We have any significant Act of God hit now and it could get downright fugly.
Thinking some more, the only real recourse for banks with LT bonds off the table is for them to double-down on the mortgage market and buy Mortgaged Backed Securities (MBS), which has its own apparent risks. Other corporate paper would normally be an option and in some cases may have less risk than anything else out there...but you are not going to get that great a return on the top shelf paper, so eating more risk for a juicier return just tilts the scales back to more risk than reward. But I see part of Operation Twist is the Fed reinvesting early payment of mortgage securities back into debt issued by Fannie Mae and Freddie Mac, so MBS looks the obvious strategy for banks to employ. Can't say I really like that option, but the options for banks are contracting.
The Fed is obviously going all-in and hoping lower LT rates stimulate lending, but as I said before I just don't see much appetite for that, so banks get their margins flattened and no new lending volume which could make up the difference seems likely to roll in anytime soon.
God forbid ST rates start climbing! Otherwise their margins will go negative, then it'll be headless chicken time.