For me, it's a combination of "resigned" and "anxious."
I'm resigned to the fact that this team appears to be on its way out. They had a good run - a better one, in fact, than perhaps we could have realistically hoped for back when the Big 3 got together. We got a championship out of it, so we can't really complain. The window was only supposed to be 3 years and we got an extra year of contention, even if it's rather weak contention. Two finals appearances is nothing to whine about.
I'm anxious because I want to see what comes next, and I kind of want to just skip ahead to the next chapter. I don't want to deal with the stress and heartbreak of seeing this team fall short and the chaos of the initial building process. I want to jump right to the point when this team will be the next Portland, OKC, Denver, or even Houston. I hope that's what we're headed for, anyway. I hope that this team doesn't become another Indiana, or Milwaukee, or Detroit. I could even get excited for a Celtics team that resembles the current Wizards - burgeoning with talented prospects but terrible and disorganized at the moment. I just want to be there so I can envision a shining future.
At the moment all I can clearly look forward to is a disheartening playoff burnout and a period of a few years (maybe more) where the team flounders in quasi-mediocrity. I'm praying that Danny is bold enough to make the moves that will make this team awful, and then exciting, and hopefully, someday, great.