I'm not so concerned about a third film, I'm sure we'll get another Bad Robot production. A 4th on the other hand...
Well, a fourth doesn't depend much at all on what happens this summer.
I kind of hope they change direction every decade or so from here on out (and didn't Abrams sign up around 2006/2007), which is not to say that the Bad Robot folks should step away - just let newer writers/directors/designers in on the Franchise to keep it fresh. A fourth movie's a good time to do that.