I think you are reading to much from Doc's words.
Rivers said he can envision the team signing both
It's the right thing to say. That way, you keep all of the options open. It's not like he is going to say: 'We are talking to Terry because we think Ray will leave, but if Ray stays we don't need Terry'.
Btw, those trades ideas involving Bradley are ridiculous. You don't trade your 21y old starting SG for a chance to strengthen your bench.
Millsap and Josh Smith is strengthening your bench?
ok.... 
Josh Smith is like candy. You want to eat it, right up until the dentist drills your teeth due to cavities.
The Celtics have made big mistakes in the past, trading youth for experience.
Paul Westphaul for Charlie Scott, Joe Johnson,,,,,you know the kid they threw in on the Rodney Rodgers/Tony Delk trade.
Both Westphaul and Johnson, the went on to be All-Stars.
Scott lasted for a couple seasons. Contributed to the 76 Championship. But he wasn't an upgrade over Westphaul. Losing Joe Johnson as a throw in to the Rodgers/ Delk combination: do I need to say more?
Avery Bradley is a rare player. He plays relentless end line to endline defense. Reminds one of Gary Payton, minus the point guard skills.
Unless Josh Smith is willing to sign an extension, or Milsap is committed to being in Boston long term. I wouldn't do it.
And I hope Danny won't either.