This is certainly possible, but several things need to happen for it to be plausible.
First, Danny has to fail in adding a few really good players to the roster this season that would make the Celtics contenders and satisfy Rondo that they were headed in the right direction.
Second, Danny would have to believe Rondo was not worth the Max and that he would not stay long enough for him to rebuild the team in any case.
Third, Rondo and his agent would have to be certain that there is a team out there willing to give him a max contract. That team would also need to be a contender and have pieces in place.
Fourth, Danny would need to find a team that was willing to give him 'value' for Rondo.
I don't see Rondo as a guy who is just going for the money. He certainly wants to be paid, but playing for a championship is also right there on his list. Danny has a proven track record of building playoff capable teams. That would indicate that unless there is an unknown factor such as a new 'secret big three plan' unfolding elsewhere that Rondo will get the best payday and best shot at playing for a contender by staying in Boston after all.
I think Danny will or already is quietly checking the market for Rondo's value as he moves forward on all fronts. This trade possibility will dramatically effect the draft and trades for the Celtics so I think it will be soon resolved if there is any grain of truth here.
Oh almost forgot, this guy is full of beans. He has no source, Just one mans opinion.