According to Weekly Young Magazine No.29, the fourth season of Minami-ke was announced to be aired this winter (i.e. from January 2013). A new OVA will also be released on October 5th. The OVA will be bundled with the tenth volume of the original manga.
Moe blobs were dominating the anime scene even when Minami ke was airing. So I don't think we'll have to worry about that. I'm surprised that they're making even more of this stuff though... they've already made it to death and all of that.
I'll repeat the sentiment about the superiority of the first series but add some optimism with my hopes that this series will bring back some of that quality. Of course, I haven't even properly watched the "3rd season" yet.
They're not remotely as bad as the knee-jerk reaction they seem to elicit. The major problem with season two was damned Fuyuki, who just sucked the fun out of every Okawari scene he was in. I still really enjoyed the rest of it though, and I remember liking Okaeri quite a lot.
Totally agree with jmal. They're not bad at all. Everyone should watch them and judge on your own opinion.