Keep in mind that's for Germany, which is far smaller than the US.
Based on this Stanford study, if you interconnect wind farms across a large enough area you can count on about a third to a half of total output as baseload generation with availability similar to that of baseload coal.
http://web.stanford.edu/group/efmh/winds/aj07_jamc.pdf
I imagine as the area was larger, the amount that could be relied on as baseload would grow. The same likely applies to other solar/wind combos when being used as load following generators in regions that have daily peaks.
Here's a paper that discusses meeting all demand with renewable energy. There's a very interesting graph on page 1172 the shows a mix of renewables meeting 100% of California's electricity requirements with a backup generation provided by natural gas.
http://web.stanford.edu/group/efmh/jacobson/Articles/I/DJEnPolicyPt2.pdf
On this page there's a graph showing houring renewable generation in CA.
http://www.caiso.com/outlook/outlook.html
The combined renewable output from today actually looks pretty close to what baseload would be. Wind is high in the evening, when solar isn't generating, and as solar ramps up wind dies down. All other renewable generators are flat and provide normal baseload.
To get to 100% we'll need to install enough to account for the amount of energy generated by thermal+imports in this pdf.
http://content.caiso.com/green/renewrpt/DailyRenewablesWatch.pdf
It's difficult, since we'll need to install ~8x existing capacity of wind/PV/solar thermal, but not impossible. Technically we may even be able to only replace a fraction of imported energy since a lot of that is likely hydro from the PNW.
The larger the area, the easier it tends to be to integrate distributed renewables and provide power when people use it.