I shouldn't say "the end", I'm sure the faithful practicioneers of " turn out the base" campaign strategies will faithfully repeat the same campaign mistakes for a few more election cycles. In fact, they'll probably try to work that declining base a little harder, following the usual "if it don't move, get a bigger hammer" logic.
That's the link to a meta-poll (polling results from several polls combined) of party ID (identification). If you look back to election day 2008, Democrats led with about 37%, Independents at around 33%, and Republicans around 27%... About what you expect would produce a democratic landslide. On election day in 2010, Independents had taken over the lead at around 37%, Democrats at 33%, and Republicans at 26%. The handwriting was on the wall even then, and since then Independent's numbers are skyrocketing to 41%, with Democrats trailing at 31% and Republicans at 24%.
About now somebody in the back row will snidely ask "If republicans were in 3rd place, how'd they win back the Congress and a bunch a senate seats?" May I refer you to our next graph from the same source, voter ID among registered and likely voters:
Clearly, the Republicans do a better job of getting themselves to the polls, lotsa Independents stayed home on election day, and the Democratic turnout was somewhere in between. But that was then, when Independent's were 37% of "all adults" . Today they've passed 40% and the meteoric rise of the Independent voter continues. I suspect that 40% was the tipping point, the point at which campaign resources are better spent wooing Independents rather than trying to drive the base to the polls (sometimes literally). The old base strategies may work for the Republicans- in the typical election where less than half the eligible voters bother to vote, a reliable base of a quarter of the eligible voters is a (barely) winning combination for the Republicans. For the Democrats, the ol' base strategy didn't work in 2010 and may never work again. For years I did GOTV in places like the 58th and 61st districts in Minneapolis' inner city, districts that voted 70% or better democratic if you could get them out to vote. We had Democratic turnout in those districts in 2008 like we hadn't seen in years. In 2010 in those districts and similar ones around the country Democratic turnout was half what it was in 2008.
So the "turnout the base" strategy is probably no longer a path to victory for Democrats. I loved it while it lasted, but it's time for Democrats to play to the "mushy middle"... The old strategies simply no longer work. And work the "middle" is what Democrats need to do, here's Obama's popularity among Independents: