I see a 6 seat loss as a decent results for Dems leaving them in a good position for 2016. 7-9 seat loss things get dicier for Dems making it an even more uphill climb for 2016. I've been resigned to losing the Senate for awhile now and am just hoping to limit our losses for 2016.
I largely agree with your post. The Democrats are being forced to defend or attempt to gain seats in states that aren't easy for us to win in, in a year bad for us nationally. We just don't have the seats to lose, and so I've thought we were going to lose the majority for awhile. That being said, as you mentioned, ideally we won't lose too many, and thus will be positioned for better year in 2016 (provided nothing terrible happens in between no and then and 2016 ends up being some sort of reverse 2008).