I tend to take any highly partisan news source (such as the Liberal publication 'New Republic', which published this article) with several grains of salt, never mind the proverbial one...
The article was, indeed, worth reading, but its theme - the demise of the NRA - strikes me as pie-in-the-sky and about as comical and maudlin-partisan as one can get...
I saw some decent citations in there for shifting popularity polls for several Senators right after the 'No' vote but nothing indicating the tidal wave that the publishers would like to convince folks is unfolding even now...
As much anecdote and wishful-thinking-disguised-as-logic as actual fact or relevant trending-history...
The thing was well-written and made some good points but it also suffers from some indulgence in over-dramatization and pontificating that betrayed its partisanship very early-on in the narrative...
But, as I said (and as the OP first pointed out)... a good and enjoyable read.
I think the main points to take from this are:
#1 - the NRA has NEVER had an opponent who could match their spending. Now they have one who could match it 100 times over.
#2 - the ads from Bloomberg's group have only just begun, and already have had affect.
Note that he plans on heavily funding Democrats Landreau and Kagen because they voted for the background checks, and plans on heavily funding the defeat of Democrats Pryor and Begich for opposing it.
So it's a non-partisan, single issue group with unlimited finances.